What should I do here?

[Power]

If you have exausted your other resources in troubleshooting it and don't have a clue, then yes, I would go back to the shop. If they are a reputable shop like you imply, and they have treated you good before then most likely they should fix it for no charge. Thats if its the same problem like you said. Shops like that tend to be aware of the power of "word-of-mouth". If they charge you twice to fix the same thing you tell your friends who tell their friends....etc. Good luck getting it fixed.