The only problem was some sort of update assistant error that came up halfway through. I just rebooted and went back to EFI and the installation looked like it carried on where it left off.I wonder if you have a bad motherboard? Did you have problems with the install? Also, what SSD are you using and is the SSD installed with an adapter?
What’s your set up?
Did you format the drive correctly?
Some of these questions have obvious answers but trying to rule out the obvious.
I'm using an MX500, same as I was using before, it goes into the normal SATA cable.
My setup is mid 2012 MBP 9,1 with 16 GB 1600 MHz DDR3 ram and 1tb SSD.
Drive was formatted GUID APFS.
I get an error when trying to run the hardware test but I've just seen that pressing option-D can run the hardware test from the internet so I will see if that works when I get a second.