Can't reprogram key fob for central locking/alarm

[dreamkast 5]

I hadn't driven my E36 for a month and the battery died which resulted in what seems to be a whole system reset. My key fob would no longer activate my central locking or alarm. I've been trying to reprogram it using every procedure I've come across on the net but nothing has worked so far. Here a few things I've tried:

Have been leaving the battery disconnected so I open the boot and reconnect. The car's hazard lights will start flashing with no siren (haven't heard the siren ever since the battery died anyway).

Then I tried a number of procedures:

Open the boot, open the drivers door, get in and close door, put key in and turn to 'on' (dashboard lights up) five times quickly, open drivers door and close again (the alarm light on the centre console flashes differently, I haven't been able to tell how), pull key out (have leaved in as well) and using my three button key I hold the unlock while pressing the lock button three times then let go and see the remote light slowly flash, get out of the car and either close the drivers door or leave it open and go close the boot and then the drivers door if I need to.

Test the remotes and never work. The siren doesn't chirp after the five key on-offs. Same thing when I try more simple procedures without the boot open or much door opening and closing. I feel like I'm close with the way the alarm central console light changes its flashes; it varies between a consistent on-off and two or three quick on-ons before one longer off. I think there was only one time I started the procedure and the car didn't have its hazards flashing and the alarm light on.

Does anyone know any other procedures or if something might be wrong with the car?

[kimmybmw 0]

unsure if this will help, mates car had aftermarket mongoose alarm, and after stripping whole car couldn't find fault, so in the end i put key in passenger door and pushed the button and it worked!!!

5 hours of stripping out car, and could of fixed issue in 2 secs lol

give it a go