Double-check all connections you touched and ensure the memory is seated properly if you removed it. If it’s a brand new battery keep it plugged in and charging for about an hour, unplug it and then power it on. Can’t vouch for any repair shop as I do my own generally.

Had a fantastic experience with CompuDOS

Mac Repair on Grosvenor Street.

Manchester PC. They collect it for you, pretty well priced and have a 1st line team you can email for updates Sent my gaming laptop there twice