Nokia 3310 automatic turns off after start
 

I have a Nokia 3310, witch after about 3 seconds turns off

1. I press the switch.
2. The "Insert SIM card" message appears
3. After 3 seconds the phone switches off.

Another switch-on does not require removing the battery, which indicates a hardware fault /not software/.
Battery contact and battery tested. As I remember, the watchdog detects a problem and does not allow further work. It required replacing the item on the board. Perhaps someone will tell me how to remove such a problem and which pice may be faulty.

watchdog issue stays for 30 sec not 3 sec , anyway seems software issue . you need to flash your phone first .

post result

I've done the flashing process with no errors.
There is no changes.