In a nutshell! This summer we had a thunder and lightning storm during which our neighbors tree was hit. Of the nine houses in our area 3 of us had damaged garage door openers. My house house 2 bad, one did nothing the other only went up and never went down again. I had 4 blown sensors ($35 from sears) and 2 blown pc boards ($70 each from Sears).
Being a tech and lucky I was able to fix one of my pc boards.
I may be cheaper to replace the whole unit. Good Luck