Laptop won't respond after having it repaired from water damage

I spilled liquid on my laptop (beer) and got it sent away for repair. Before i had it repaired it would just cut out and the keys would stick. when i got it back it has a new battery and keyboard. When i turned it on for the first time (didnt plug charger in) it was very slow and unresponsive and wouldn't load any programs, it was just struggling along and was unusable. i started it in safe mode and it was okay but obviously i can't use it in safe mode all the time. Has it not been fully repaired? or is it just because its the first time i turned it on in 6 months? does it need to be plugged into the power point for the time? any help would be appreciated.