Hi there , friend has a rancher AT 420 that his wife uses around their farm, I’m no pro but he got a new one instead of attempting to fix and wants to sell me this one at a reasonable price that I can afford .

So the bike was parked up for a few months in his garage and it cranks and starts perfectly but when you Press the drive selector buttons ( up or down ) into drive or reverse nothing happens , there’s just a horizontal line on the screen " —- ". Does anyone know how to fix this ?