Help - can't open the boot

The other day all the doors (except the driver's door) and boot wouldn't unlock with the key. I don't use the remote and the alarm is disabled.

Managed to get doors working by opening from inside but can't see a way of doing that for bootlid.

Any ideas? Little tricks? Cheers
Hi, I got the boot open. However, I should have said - the battery is fine, no issues with battery.

I suspect a relày / earth / broken cable.