Hardware Error problem Toshiba laptop

Good day!
I am a student and frankly speaking, I cannot afford the payment that the computer technician had asked me to, to rectify the problem that my Toshiba laptop is experiencing at the moment. Here is what happened to my laptop. I installed a 500GB external hard disk into it.
When the installation was finished, the command manager asked me to restart it for the new installed hardware to take effect. During the booting process, the blue screen appeared with the message that there is a hardware error occurred. I immediately used the recovery disk that I have to recover the original settings of my laptop but the same error in hardware had been occurring.
What will I do? The amount that the technician was asking is too much. I am thinking to fix it on my own. Thanks for the valuable help.
