Perils of ebay

Recently sold my old android tablet on ebay. Didn't hear anything for a while and then the purchaser contacted me to tell me the tablet had stopped working. I've tried to be helpful, even sent a second charger in case it helped. Apparently nothing will charge the tablet and now his emails are inferring that it must have been opened, which is untrue and that it was damaged, which is also untrue.

Told him I can't help any further.