2003 Kia Spectra Trunk

I need to replace the Pass side taillight assembly but the trunk seems to be jammed shut. Any ideas on how to get it open? The key turns, but the lock just clicks.

If you live in cold country, it’s probably frozen shut. Parking in a warm garage would free it. Pouring hot water into the crack all around the lid and quickly pulling it open might work or make it worse if it’s really, really cold.