Question Laptop shutdown without warning

[fadh]

Specs
Desktop-u48h5vs
Intel i5-2410m cpu @ 2.30ghz
4gb ram
64 bit
Windows 10 pro 20h2 ver

Hello. My laptop is Toshiba Satellite L745, I buy it second hand 3years ago. Just a month ago I clean the fan and replace the thermal paste(arctic mx2) , install new windows 10 from usb and everything is fine, but within this few weeks it keep turning off by itself and no blue screen or any warning. Today I get about an hour and then I try turn it back on and got like 8 minute. No heat problem, on battery or plug in is just the same. I try using most of suggestion on google but got nothing, I hope someone could help me get at least a closure on what is the actual problem..

Update:

I got the kernel power 41 critical

Is my laptop is beyond help?

 

[Xbox and Windows Gamer]

Laptop specs? Maybe something is shutting down inside that is required causing the whole laptop to shut down or maybe something malfunctions every now and then out of the blue (more likely, as the very low time before power off seems like hardware such as the battery or something else might be acting up)
What thermal paste and fan did you buy for the replacement? It may be acting up already if its a not very long lasting fan/thermal grease. The system may shut down to prevent any possible overheating (less likely as you said no heat problem)

 

[fadh]

Laptop specs? Maybe something is shutting down inside that is required causing the whole laptop to shut down or maybe something malfunctions every now and then out of the blue (more likely, as the very low time before power off seems like hardware such as the battery or something else might be acting up)
What thermal paste and fan did you buy for the replacement? It may be acting up already if its a not very long lasting fan/thermal grease. The system may shut down to prevent any possible overheating (less likely as you said no heat problem)

Just edit the post. I clean the fan not replace it, I use arctic mx2. I always use plug in without battery, but I though if I use both it will fix the problem, but it doesn't.