Is it showing any life? Get a digital camera, point it at the transmitter and watch the viewer while pressing buttons on the remote, you will see the transmitter blink if it's working. It might just be some keys which aren't working, in which case look at the pad contacts (once you have it apart) or if it's all keys check you are getting good contact on the battery terminals. A little rub on them with some fine sandpaper might do the trick if it's the battery contacts that are corroded.
Garrard 401, Jelco 750 with Shuggie, Ortofon 2M Black / ZYX Yatra 100, Project Phono RS with Sigma22 Linear PS, RPi3 + DigiOne + Linear PS, RPi3/1Tb SSD with PiCorePlayer + Linear PS, Perreaux Eloquence 250i 40th Anniversary with ES9038Pro DAC, DCG3 Pre-Amp, Neurochrome 8x2 Pre-Amp, Neurochrome 686 Power amp, Benchmark DAC2 HGC, Primare V25 CD player, Monitor Audio PL300, Sjostrom DCT03 DC Blocker.