Boot lid does not open

Hi all,

I have a problem with the boot lid of my 147:
if I try to unlock the boot lid using either the remote control or the
button at the car's panel and the car has not been moved shortly before,
the lid does not open and the indicator lights are flashing once.
If you do the same procedure shortly after driving, it works!
The front doors can be unlocked without any problems.

Can this be a battery problem?

Regards,
Florian