I was trying to get OpenWRT working on my Bullet M2, but was having issues. So I heard there was a serial port on the board that you can use to grab debug information. I proceeded to open the sucker up, and at first was doing it wrong.
The proper way is by taking the ring off near the N connector for the antenna. I used some vice grips and it came off rather easily with some muscle. Here’s a photo with the ring circled in red. ;D
Once the ring is off, you simple push the N connector and the board will slide out of the enclosure.
I haven’t found a good TTL to RS232 converter that has decent cables. There are some but I’ve yet to research them fully. You also need the proper pinout, which I don’t know yet so if you have a solution for both please post a comment. Thanks!