Transmission errors on a Tomy Ombnibot 5402

Hello. Recently, I have been working an a refurbishment project of an old Omnibot 5402 which I bought from Ebay. Having got the main power working again, a long with its remote, I have come across a problem which I don’t think I have the capabilities to solve. This issue seems to be that, once turned on, the Omnibot is incredibly inconsistent with how it behaves. Sometimes, it does nothing, makes no noise and doesn’t move. Other times, it will beep whenever I press any button on the remote (and its eyes will light up). Yet mainly it makes a loud static sound until it is turned off of RC mode and onto tape mode. Rarely, however, it works fine, with all capabilities, in any mode in any setting, moving around and making noises as the remote control tells it to do… when the antennas are touching. Because of this, it seems to me to be a transmission error between the bot and the remote, something that sends of incoherent signals that only work some of the time. I must add, the Omnibot which I bought is and English one, while the remote I believe is French (if that makes any difference). I would love some help as I m really struggling and would love to get it fixed.