Welcome to the forum (name?). Your issue will most definitely be with the seat control module, specifically the batteries in the module will have leaked and damaged the circuit board in it. This fault has been discussed many times in the past on this forum, if you do a search of the forum posts you will find lots of information on it. Also, the factory workshop manuals are available free online at rrtechnical.info, and also heritage.bentleymotors.com. To get at the seat control module you lift the seat base, the workshop manual will give you directions on how to do it. You don't have to remove the whole seat to get at the module which is under the seat base cushion.