pc only works when plugged in after new ssd

So I bought new ssd instead of the old one, to have 512 GB memory. I moved the old stuff to the new ssd and after changing them, tried to start my pc. But unfortunately it worked only while plugged in. I changed the ssd to the old one and tried again, and it worked. Then changed them again and it would not work. When I put the old ssd one more time it didn’t work, and now I can’t use my PC unless it’s plugged in. Why could that happen?