[Acer Iconia A500] rick0612:
I have been working on changing the Operating system on my A500 for the past 3 days. I'm retired and it really has been three 12 hour days. The forum has been a font of information but it is scattered and confusing to someone new like me. I have been writing what I did and wanted to share it with the other noobs. Of course I had to register on the forum first. So today is my first day registered and here is my first post.

A procedure for changing the ROM in an A500

This procedure is for Windows. It can be done on Mac and Linux but we're not going there. It uses Afterota v1.09 by gersma. Although the program is great, there is really no explanation of how it works or how to use it. I hope this procedure helps the noobs like me.

You can install Honeycomb (HC), Ice Cream Sandwich (ICS) or Jelly Bean (JB). I'm not giving links because they change, are unavailable or otherwise wrong. Plus this is written to be printed and followed on paper because there is a PC restart involved; also I sometimes lose my place while online. If you can keep it straight, more power to you. I'm writing this for complete noobs. Admit it, we were not born knowing this stuff. As a complete noob I am also assuming you and I have not changed our A500 in any way other than the normal updates from Acer and Google.

Now for the disclaimer:

You do this at your own risk. If you point a finger at me and start yelling, I will hold up a mirror facing you so you can see who is to blame.

Prep your A500 for the procedure

For safety sake, remove the micro SD card if you have one installed.

Plug the A500 in to AC power, power it ON and ensure it is fully charged. Keep the tablet powered from AC. Ensuring it is fully charged is insurance against accidental power loss. You don't want to loose power while doing this procedure or your tablet could become a paperweight. Place the tablet close to the PC (notebook or desktop) you will be using for the procedure. You're going to connect the tablet and PC together with a USB cable later. The best cable is the one that came with the A500, the one with the micro USB end and regular USB at the other. If you use something different, make sure it is a good quality cable.

The next step is to set the tablet to accept changes. Tap Apps → Settings → Developer options → USB Debugging.

If your tablet is password protected, disable it now. You'll have to set it up again anyway after the change.

Prep your PC for the procedure

Download and install the USB drivers for the A500 from acer.com.

Go to the xda-developers.com forum and download Afterota. You can search for the program. It doesn't require installation, it just runs as is.

Another thing to look up is recovery apps. There are a number of them and they all do the same thing in slightly different ways. Afterota v1.09 offers four, Thor 1.7.3 (touch screen), TWRP 2.1.3-ICS (touch screen), Ra v3.1.7 (touch screen) and Pub v0.2 (Vol and power button). I discuss recovery later.

Next we need a ROM to load. Again, go to xda-developers.com and search for one that interests you. They are under the Iconia A500 Development section. When this was written, I installed JB 4.1.2. I highly suggest you read up on the ROM you want. Check for status, useability, included apps, excluded apps, bootloader requirement (for this procedure ICS), etc. When you finally download your preferred ROM, do not extract it. You will be using it in the zipped form.

I have seen a zip file called gapps (Google apps) on xda-developers.com. It appears to be needed for some ROMs. Again, download it if necessary but do not unzip it. The JB ROM I used specifically stated the gapps were included.

The next step is to disable User Account Control (UAC) in Windows. Go to Control Panel → User Accounts → Change User Account Control settings and drag the slider to the bottom. You will have to restart the PC for changes to take effect.

The procedure

Install bootloader and recovery

It looks like you're ready to proceed.

Connect the PC and tablet together with the USB cable. Place the small end into the tablet and the larger end in a PC USB port. You will see the device drivers load and Windows Explorer will ask what to do. Click on Open device to view files.

At this time, you can browse the tablet using Windows Explorer. Most everything you want to see is on the Internal storage partition. If you have a micro SD card inserted, it will show as SD card. I strongly suggest you check through the folders for any data, documents, music, videos, etc that you may want to safeguard. Copy the folders and/or files to the PC. If they get destroyed on the tablet, you can copy them back later.

Run Afterota. The first thing Afterota does is collect information from your A500. It takes a few moments so be patient. When done, it will save the text file, AcerIDs, to your desktop. This file is very important. It will have the tablet's serial number, CPUID, SBK and other stuff. It is a very good idea to save it and/or print it for future use; it could get overwritten later.

There are five tabs in the Afterota window. Info – where we just collected the information, Stock – to go back to HC, Standard – where we will be going next, Advanced – unbrick and other stuff and About.

In Standard we need to choose a bootloader.

What exactly is a bootloader and why do we need it? A bootloader is akin to the starter of a vehicle. You insert your key into the ignition and turn it to start the engine. A bootloader starts the operating system (engine) of your tablet. If you change the engine in your vehicle, you need to install a compatible starter. We are going to be changing the engine of your tablet, so we need a new starter as well.

Afterota v1.09 has 2 bootloaders. One is just for HC. The other one is for ICS and presumably for JB. Make sure your ROM will use an ICS bootloader. You'll notice the Bootloader ICS options have the same bootloader version but different recovery apps.

Recovery here is and isn't the same thing as in Windows. From the factory, you use the Acer Recovery app to get your A500 back to original factory setup like in Windows. You use one of these Afterota recoveries to install a new operating system (OS). The differences in the Afterota recovery apps is the way they present options. The only one I've used is Twrp v2.1.3. It has a nice GUI. You should have read up on them all and decided for yourself which to use.

Click on the A50x box for the recovery you want and the program will do the install.

Once the program is done it will reread the tablet and generate a new AcerIDs file. Keep the original file, for some reason the second one doesn't get the tablet serial number. Of course, you can keep both. You can close Afterota now.

Install ROM

The next step is to copy your zipped ROM to the Internal storage of the A500 tablet. Do not put it in the SD card. You can also put the gapps zip file here now if you need it.

Disconnect the USB cable and power OFF the tablet.

Press and hold Volume down side of the Volume button (the side closest to the power button) while pressing power on. Wait til you see the booting recovery image message then release the buttons. You are now in the recovery app you chose earlier.

The words and menus may differ between recovery apps but the functions are the same. You will probably have to move between menus. Just take your time and think about what you are doing and you should be fine.

Wipe, Erase or Delete caches and do a Factory Reset. Next, format the system and flexrom.

Now, traverse to where you see the menu option Install Zip from SD (or something to that effect). Choose your ROM and install it. If you put the zipped gapps on the tablet, you can install that as well. If not, you can do that later.

Once successful, boot up normally to your new OS. The first boot takes a very long time. Be patient.

Time for thanks. Thanks to gersma for Afterota. Thanks to all the developers of the booloaders, recoveries and ROMs. Especially thanks for sharing your work.