[Samsung Galaxy M30 Guides, News, & Discussion] thvardhan:
Hi all,

This is a brief guide on what are some things that could go wrong if you decide to flash a new ROM especially GSI as they are quite buggy at the time of writing this post. I'll try to mention as many issues as I can but if something remains, please feel free to write them in the reply.

The guide is aimed for complete beginners who were trying to flash something and are now stuck OR who just want to know what to be prepared for and not to panic. if you are experienced you might not need it but it might just help you with something.

also, as always, I AM NOT RESPONSIBLE IF SOMETHING DOES NOT WORK. YOU ARE RESPONSIBLE FOR YOUR OWN ACTIONS.

So let's start with the most common problem. Bootloops!

1 - Bootloops :

What happens? : The title is pretty self-explanatory. You know you are in a bootloop if your phone turns off automatically as soon as it turned on. This generally happens BEFORE the phone actually boots up i.e. in the booting screen but could also happen after the phone completely turned on. There are various causes for this it may be due to a bug in the ROM or missing system files.

How to fix? : If you are flashing a custom ROM then you may want to reboot back to TWRP, wipe and flash it again. It works sometimes if there was an issue with the files.

I am unable to reboot to TWRP my phone is stuck even long pressing the power button does not shut it down! :crying::crying: : well if you are stuck you don't actually need to open the back panel to remove the battery or wait for it to die those won't help. all you need to do is wait for the phone to turn off and IMMEDIATELY press and hold the VOLUME UP and POWER button that should get you into TWRP if that doesn't work then you can try pressing and holding the VOLUME UP + DOWN + POWER key as the phone is about to turn on. it might boot you into download mode. if that does not work as well then as the phone is about to turn on, press and hold VOLUME UP + DOWN and plug the phone into PC that will get you booted into download mode eventually. Once you have access to one of these you can continue doing whatever you were doing. To reset everything back to normal (stock, like a new phone) checkout the solution listed below.

2 - I was doing something and now my phone is stuck at charging mode :

What happens? : This has happened to me while flashing PHH GSI. My phone was plugged into the charger and I restarted the phone. turns out it was a fatal mistake for the bugged gsi. The phone now only showed a battery icon that was charging very similar to the one that you would see if your phone is out of battery and you put it to charge. This happens before the phone actually turns on. usually, once you unplug the charger the phone automatically restarts but in my case it didn't. It was stuck at that screen with no way out.

How to fix? : turns out it's pretty easy, it might seem like its doing NOTHING, not responding to power buttons or anything but internally it is. Surprisingly, if you press and hold the VOL UP + DOWN + plug it into the PC it would get you into the download mode.

3 - I flashed GSI and ... :

What happens? : There are MANY things that can go wrong with GSI if you are a beginner I would suggest you stay away from GSI until it supports the device better. For me, I flashed PHH gsi and it went smoothly I booted in but as soon as I was finishing the setup adding fingerprint the ROM went into bootloop. you know how to fix this now. if nothing works, just refer to the reset solution listed below.

4 - "Custom binary blocked by FRP lock" :

What happens? : This usually (at least with me) happens when you are trying to flash something but forget to flash the DmVerity thing. The phone won't turn on and going to download mode will throw you with a line saying FRP lock.

How to fix? : At this point, trying to install custom binaries with Odin probably won't help as for me it simply stated that you cant install custom binaries only Samsung official updates are allowed or something similar. There might be a better/easy solution to this but I found doing a stock reset with Odin worked great. It is given below refer to that.

5 - Phone is in "Emergency firmware recovery" Mode :

What happens? : Turning on the phone throws you into a cyan screen saying that your phone needs emergency firmware recovery which can be done using Samsung smart switch

How to fix? : I believe it is a fantasy way of Samsung saying that your phone is almost dead and nothing remains on it. Fear not, turns out that cyan screen is actually the download mode. :D so that's a win you don't even have to boot to download mode just connect your phone to pc odin and follow the reset to stock firmware as mentioned below.

6 - I am back in some OS but my internal memory is shortened!!!

What happens? : well you are in the os you wanted but if you check the storage it appears to be shortened. i.e. if your phone has 64gb internal memory it might appear as 30gb or 20gb.

How to fix? : This is a problem caused by missing PIT file in odin. I would not suggest you to manually download the PIT file from somewhere and flash it using odin because doing so got me stuck in the FRP LOCK (4th) situation. I would suggest that you flash the stock firmware using the method given below.

MASTER SOLUTION/RESET TO STOCK FIRMWARE: if you are new to modding I would suggest that you download the stock firmware files from here BEFORE doing anything as the files exceed more than 3GB in size and not everyone has fast internet. if anything goes wrong and you have access to download mode you can follow this and get everything back to stock. Download the stock file AFH given at the link. once you download the stock firmware you just need to extract it and put the respective files in odin and begin flash. it will RESET everything and make it a new phone. I've tried this method and it works always for me.

That concludes my guide. if anyone knows any better solutions to these problems or think I've written something wrong please feel free to correct me. I've faced all of these issues back to back when I tried flashing a GSI and was able to fix all of them so this is just my personal experience.

Lastly, don't panic if something happens wrong happens there is probably a way to fix it.