2005 Magna. Usually open the boot from button in glove box. When car has been in the sun for a while, the boot wont open, no sound when I press the button. But when it cools down its ok.

How do these releases work and where should I start looking?

Electrical connection to motor at base of aerial. Motor pulls a cable. Lock probably set up too tight for the motor to open it.

Get someone to look at the motor in the boot when you press the button (or vice versa) and see if it does anything at all.
Could be that when the cable is hot it expands and is too loose to completely de-latch the boot?

Get someone to look at the motor in the boot when you press the button (or vice versa) and see if it does anything at all.
Could be that when the cable is hot it expands and is too loose to completely de-latch the boot?

This can be achieved solo by hitting the boot release button on the remote.

Assuming the remote works, yeah

Mine did that, same with the gas door release, runs off the same motor. So i just bought another one. Works great! I think the problem was that cable that pulls it was starting to tear.

I'll also say that, since there's very few Magna(Diamante's) here in the usa. I found 1 piece on eBay, so I had to deal with the 60 dollar price tag.

And I assume that they didn't change too much on the newer Magna's, mine's a 2001. So if what I said helps, good. If not, sorry wish I could've.