Need to take the GM5 Module out from above the fuse board behind the glovebox to check what model of GM5 you have, there are 2 types. Then either replace with a good used one or send yours off to Mervyn in Harrogate at Autoelectron for repair. The usual problem with them are the window relays or central locking that he replaces so worth checking with him if he also repairs the window trap components before sending it off. The modules are plug and play so no coding required for them to work.
Autoelectron
Address: 28 Camwal Rd, Harrogate HG1 4PT
Phone: 07788 922927
He also trades on ebay here
https://www.ebay.co.uk/itm/276430964151?_skw=bmw+e85+gm5+module&epid=8008790265&itmmeta=01JMFD7P9W95T3FAB32TBQDSFX&hash=item405c91c5b7:g:zNUAAMXQ9rVQ42AG&itmprp=enc%3AAQAKAAAA8FkggFvd1GGDu0w3yXCmi1c5%2B0x9x7Ga8%2B6V68ADCtnEkjXRDYTtlWlsVU3kEJV%2B6Y5Rlzx6EtQo1G5ry08oZJUsdDb54G4KbO2wSGTUxVfK%2FobyehzSs2%2BVRJrzq%2FkKVC6pg13bqsna%2F2T6uRtcKagqDhdNu1sS0WpXQPhpNneqCerPMHWBxQYEsLwSaM85JxrPyLQvcZ1LCBa9NlrP32AZFeBWlaRJQfhqJg4HAmLvxg2XImu3bKcluCiUinyat6GtVC3FDtGwbDaxbguociM1RhbPtHZHw2vxTNt4UVJqVzWBdPyXMILLHtbVQaodJQ%3D%3D%7Ctkp%3ABk9SR5Dlnu2jZQ