Toshiba Satellite L650-1nu - Turns Off After 4-6 Minutes

Hello, I have problem with turning off Toshiba Satellite L650-1NU, it has processor - Intel I5-480m. Part NO: PSK1JE-0GD00KPL

What I did so far:

1. Disassembled all parts and clean dust from - motherboard, cooler and heat sink.
2. Cleaned CPU and GPU from old thermal paste, I also put new one.
3. Removed battery and plenty of times pressed power button, all further tests were done with only power supply plugged on - no battery.
4. Reset BIOS settings to default.
5. Attached other power supply from different working laptop.
6. Removed and changed combinations of RAM memory.
7. Removed hard drive and CD-ROM.
8. Run laptop and detached cable from power button - read some forums with such solution for higher Toshiba model 7xx - people run laptop with multimedia bar.
9. Measured CPU temperature under Linux and memtest86 - in both cases temperature was around 65-70C where I read for this model is stable even with 90C+ temperatures - max temperature on Intel website is 105C.
10. Checked capacitors and they looked fine - no bulge.

It shutdowns no matter if running in BIOS, Windows, Linux or memtest.

Please help me, I lost ideas what it could be. I didn't update BIOS because it is risky to start procedure if it shuts down in 4-6 minutes.

Greetings and thanks for help