Also known as Ericsson P504
Gunk and green death on the speaker/mic connector, leading to poor sound performance.
Disassemble, apply some magical cleaning compound and reassemble. You will need a ball-ended allen key to remove the bolts inside the battery connector. The rest are standard flat and Phillips bolts/screws. There are some really tiny screws holding the display assembly to the main board that are easy to miss. Also, look out for the five springs. Three blade springs on the battery latch, one tiny coil spring on the speaker/mic locking mechanism and another longer coil spring holding a latch on the rear case assembly. I do not know what the latch is for, but I guess it is for some kind of radio dock.
To take the case apart, the rear case assembly goes out and then down. It is pivoting at the antenna connector. The lower part of the front and rear case need to be about 15mm apart before you can pull down on the rear case.