stm32g474met3 keeps burning out for unknown reason

[Tom12]

i have MCU circuit with stm32g474met3 as the processor, designed such that it controls the main board charging circuit and it keeps burning randomly at random times could be 5 hours or 20 minuts or even few days I cant figure out why, it burns whether its connected to the main board or not. I tested pin configuration (i.e. inputs and outputs ) and they are all defined correctly. I cant find any issue. and the scheme looks fine. i also removed the 2 0ohms resistors on UART2, and permanently shorted the boot instead of the jumper,
i don't have access to the code of the MCU but how can I electrically find the issue?

[TDK]

VSSA should be shorted to VSS. It appears to be floating in your schematic.

 

If that's not it:

What does "burn out" mean in particular here? Is something visibly damaged or is it just not doing what you expect it to? What are you expecting it to do?

[Tesla DeLorean]

>>What does "burn out" mean in particular here?

Probably the IC / silicon acting as a fusible link..

Review the NET LIST, and confirm you don't have any oddly or inconsistently named nets or islands that don't connect to others as expected.

Test continutity on a PCB, or unpopulated solder-test item.

Physical damage frequently occurs due to very high potentials and unanticipated current paths, possibly through the device itself.

[Tom12]

Update: 

i tested the burned chip and check which pins burn the processor and its randomly, meaning i check several chips and each of the chip pins sink the current at different pins unrelated to one another. i assume the damage is due to noise or other reason, if i cannot solve the issue how can i protect the pins from burning again.