Lumia 800 - Reboot while charging

[YamiCodenamed]

Here is an interesting issue that has been happening for about an hour now
Whenever I plug my phone into the charger, it remains on for 4 seconds and then crashes/restarts, boots up to the start screen and repeats that.
It has started when my phone notified me that the battery is running low and i plugged it in.
Before this the phone was idle (I haven't been using it) for about 8 hours but the game Song Arc was on the whole time.
As far as i know, the os regulates the charging process and flashing could fix it, but in that case ill loose all my apps and settings.

Is there any way to resolve it without having to soft reset or flash the phone? I kind of don't want to loose my data.
What i did so far:
- Plugged the charger in while the phone was on - crash loop
- Plugged the charger in while the phone was off - crash loop
- Plugged the phone into the pc - crash loop
- Entered qualcomm mode - its ok but there ain't much use of that but for flashing
- Hard reset - didn't work

I left the phone off now in order to see how it behaves after the battery rests. If it doesn't work, i might drain it completely and then try to charge it up

EDIT: Letting it rest did not help, going to flash a custom rom then stock rom to it in a moment
EDIT2: The custom rom does not have the problem. I guess its a system error