Display messed up after battery repair

SMC RESET

• Shut down the computer.
• Unplug the computer's power cord and ALL peripherals.
• Wait 15 seconds.
• Attach the computers power cable.
• Wait another 5 seconds and press the power button to turn on the computer.

If that doesn't work, try resetting the PRAM. (Be aware that resetting the PRAM will probably mean that you'll have to reset some of your preferences afterwards.)

PRAM RESET

• Shut down the computer.
• Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
• Turn on the computer.
• Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
• Hold the keys down until the computer restarts and you hear the startup sound for the second time.
• Release the keys.

If none of this works, I'd recommend having the computer evaluated by an Apple Authorized Service Provider. You'll find them here: https://locate.apple.com/