08 750li trunk latch is stuck

Put the key in the lock fully, push down firmly on the trunk several times and see if the key will go in any further. Either way, once you are certain the key is in fully, put turning pressure on the key while at the same time firmly forcing the trunk closed. This should free up the tension on the lock and allow you to turn the key to unlock it. I am a Certified Locksmith with over 50 years experience.

I have tried this and it partially works. I was able to get the key to turn enough to open the trunk partially but I am still unable to get into it. It will not open beyond the point where it will close automatically if released

Keep working it. You have no other options except a crowbar.

Have you been able to open the trunk trunk yet? What has happened is that the bag strap is stuck in the latching portion of the lock. The key is turning far enough to activate the electric latch retraction but is not turning far enough to overcome the physical latch that holds the trunk to the car. If you keep working at the key even though it seems to be unlocking it, you may be able to overcome the pressure on the locking portion. If you can, place something firm, but not hard metal, under the trunk as soon as the electric release activates. Take care not to bend the trunk lid or pry on it, you will just make more damage. Once you have the trunk partially ajar and 'jammed' so it cannot close, you should be able to have a small amount of room to get at the bag and latch to help you work the latch free. It's jammed and the only thing you can do is to keep working at it a bit at a time and eventually you will relieve the pressure enough to get it to release. Hope that helps or you already have it open.