HP250 G5 (Z2Y78ES). Why is my laptop turning off?

Question

laptops

I bought a laptop HP250 G5 (Z2Y78ES) a year and a half ago.
About 2 months ago it started shutting down, then the hard drive died.
I bought Kingston ssd a4 240gb.
Now everything works, but the laptop turns off during long work in programs (webstorm, atom, photoshop, chrome. What will happen when I start GULP?), after a couple of seconds it turns on itself, sometimes after such a "restart" it turns off again, and a black screen appears, flashes CAPS LOCK 3 times (googled - memory error).
Also, when charging from the network, charging disappears, then reappears.
It is worth noting that when I take out the battery and work from the network, everything is fine, the network does not disappear. But the problem with the shutdown (under load? Remains). I also tried to work from the battery. Everything is fine, but it still turns off .. I recently conducted a stress test in Hades, throttling of the processor appears at 3-4 minutes, I didn’t wait any longer, I canceled the test. Sensors show that the percentage is hot, and heats up quickly even from the browser .. I
disassembled the laptop, there is thermal paste, gray (factory?), It is not dry, I don’t think that the problem is in thermal paste ..
I don’t understand what could be the reason? What causes throttling, and what caused the death of hdd (possibly died a natural death)?
My assumptions:

1. Is something (what is responsible for powering the motherboard?) out of order, and is supplying too much voltage to the components?
   
2. I installed an ssd, and the processor cannot pull out such drives, it needs more RAM
   
3. The laptop is defective, but worked for a year
   

I am also thinking of sending it for post-warranty repairs, to where I bought it.
If you need any additional information, I am ready to provide.

Answer 1

• Dual-core Intel Core i3-5005U (2.0 GHz)
  
• RAM 4GB DDR3L-1600MHz
  
• AMD Radeon R5 M430 2 GB