Hello & Welcome to justanswer.com!
The alarm is indeed beeping because there is a problem with the circuit - probably as you suspect .
Have you tried pushing hard on the boot to be sure it is shut - and then try again?
Other than that - you will have to enter the boot from inside the car - this involves stripping out the back of the back seat - and armed with a torch and some tools - going through to the boot and releasing the clamp that holds the boot shut from either the boot itself or the body of the car --- once the boot comes open you can then deal with whatever jammed it .
I sincerely XXXXX XXXXX have helped you -
Kind rgds, MIKE
PS~Please hit ACCEPT if you are happy with my answer/advice given ~Thank you ;)