[Acer Iconia A500] sc2k:
As I've seen a few people around having some checksum erros, I decided to write a small HOWTO.

!!!

The most important information needed to recover from a bricked device is the UID

If your device is not bricked and you read this thread ensure that you have saved your UID!

!!!

​

Because some people do not read big red text, here it is once again:

GET YOUR UID even if your device is not bricked.

If you need help please contact me with PM or ask for help in this thread.

If your device does not boot anymore it may display the following checksum erros:

"LNX checksum error" - when trying to boot into normal mode

"SOS checksum error" - when trying to boot into recovery (VOL- + Power pressed)

<CASE 1> SOS checksum error

Steps:

- Switch off your device by pressing power for ~8sec

- Switch on your device and boot into normal mode

- If LNX checksum error is displayed, stop here and see <CASE 3>

- Download itsmagic (see this thread). Extract "itsmagic" to the tools folder of android sdk.

- Connect your device to your PC (Windows: drivers can be obtained from Acer website)

- If not already done, get your UID using Method 1 of "How to get the UID"

- If not already done, get a dump of mmcblk0_start (see "How to get a dump of mmcblk0_start")

- In the command window type:

adb push itsmagic /data/local
adb shell
su -
chmod 755 /data/local/itsmagic
/data/local/itsmagic
exit

- If everything went fine you should see some output of itsmagic

- Reboot and check if you can boot again

- Store your UID and mmcblk0_start to some safe place

Possible reasons for this error

- You tried to install a new recovery without calling itsmagic before

- You have not remove /system/etc/install-recovery.sh

- Your recovery partition is corrupt

<CASE 2> LNX checksum error

Steps:

- Switch off your device by pressing power for ~8sec

- Switch on your device and boot into recovery by pressing VOL- + Power

- If SOS checksum error is displayed, stop here and see <CASE 3>

If you have stock recovery:

- If not already done, get your UID using Method 2 of "How to get the UID"

- Apply an official OTA, see this thread

If you have thor's CWR:

- If not already done, get your UID using Method 1 of "How to get the UID".

- Select "reboot system now"

If you have any other recovery (that does not have itsmagic integrated):

- If not already done, get your UID using Method 1 of "How to get the UID". If Method 1 does not work, try Method 2

- DO NOT apply any official update.zip . Otherwise you will end up in <CASE 3>

- send me a PM or ask for help in this thread.

Possible reasons for this error

- You tried to install install a new kernel / stock update.zip without calling itsmagic (will not occur with thor's CWR)

<CASE 3> SOS and LNX checksum error

- If available, upload the "mmcblk0_start" dump to some file hoster (e.g. dropbox)

- Send me a PM with your UID and a link to "mmcblk0_start"

- If you do not have your UID: DO NOT connect your device to your PC:

- Pray that you are able to recover the UID from a PC the Iconia was already connected once.

- Windows: Try Method 2 of "How to get the UID" but DO NOT connect your device to your PC.

- Linux/Mac: Check old syslogs for messages where your device was connected to your PC (normally some "usb " kernel messages)​

Possible reasons for this error

- You tried to install a new kernel athough you already have a SOS checksum error

- You tried to install a new recovery altough you aleady have a LNX checksum error

How to get the UID

Method 1

- If not already done, follow the instruction "Howto install ADB" below

- In the command shell, type:

adb devices

and press RETURN

This will output something like this:

List of devices attached
370014740c00594 device

The number is your UID.

- Save this number somewhere it won't get lost

Method 2

- Connect your device to your PC and ensure that drivers are properly installed (Windows: Can be downloaded from Acer website)

Windows:

Download this tool (download link is nearly at the end of the page):

- Open the tool

- Sort after VendorID

- Find all devices with VendorID = 0502 and ProductID = 3325. Check the "Serial number" column for these devices.

Linux:

Call (as root) and see the iSerial field for Iconia.

lsusb -v

Mac:

- Should be visible in system profiler. Sadly I don't own a mac. So if anyone can help me out with this?

How to get a dump of mmcblk0_start

- If not already done, follow the instruction "Howto install ADB" below

- In the command shell, type:

adb shell
su -
dd if=/dev/block/mmcblk0 bs=512 count=13312 of=/sdcard/mmcblk0_start
exit
exit
adb pull /sdcard/mmcblk0_start .

- This will create a file "mmcblk0_start" in the tools folder of your android-sdk.

- Copy this file to some safe place

How to install ADB

1. Download android SDK from here. Windows: Download the .zip file instead of the exe file.

2. Extract android SDK somewhere

3. Open a command shell:

- Windows: Press Winkey+R . Some small window appear. Enter "cmd" and click ok. A black command promt window will open.

- Linux/Mac: Open a terminal window

4. "cd" to the "tools" folder of the android sdk by typing the following in the command shell:

- Windows:

cd "<path to tools folder>"

Sample:

cd "c:\android\android-sdk-windows\tools"

- Linux/Mac:

cd /path/to/tools/folder

5. Ensure that your device is connected, that drivers are installed and that USB debugging is enabled (on Iconia: Settings->Applications->Development->USB Debugging)