[MuseChaser]

Not to take issue w/ Humfrz, but do NOT use WD40 on your locks, unless you want to have to use it constantly from now until you bury your car. WD40 is a "works now for lubrication" product, but makes things way worse in the long run. It's a great cleaner, and it's also good for creating a barrier against water, but it's a terrible long-term lubricant.. it gums up, attracts dirt, and makes things worse. For locks, use graphite.

If your back seat is not firmly latched (and mine usually isn't), try yanking the back seat down, then crawling into the trunk and using the emergency white/yellow-ish manual release tab right near the latch. If/when you do eventually get your trunk open, don't latch your back seat anymore.. just in case!