The Pentium N3700 is BGA1170, and is not socketed. There is absolutely no chance this is going to work in LGA1150, even if you got an interposer. The N3700 is a Braswell chip, completely different from Haswell or Broadwell.
On the case of your friends PC... The N3700 CPU is soldered to the motherboard, and isn't able to be changed without specialised tools.
I would recommend a fresh install of the OS and an inspection of the temperatures.
If they happen to be Linux - Braswell has a sleep state bug that will cause random crashes at idle. There are fixes for this if you search online.