Presumably you are trying to reset it so that you can enter the code?
If it automatically switches itself off after a shortish period of time ( one hour?), then you are going to have to remove it from the car and wire it up to a battery supply on your workbench . Switch it ON as you would if you intended to enter a code ( ON switch plus another?) then leave it UNDISTURBED for as long as it takes to restore.
There might be a quicker method ..Contact for details via
