I do believe the phones can become magnetized by cases with magnetic latches.
I had a compass problem with my Razr Maxx. Like several other people everything worked well for a bit then the compass started jumping all around and finally quit all together. I called Motorola and was told they were not aware of any problems as none had been reported. I told the tech there are many people on the web complaining about the issue. He blamed the problem on 3rd party software and suggested I do a full factory reset. I did not want to do a full reset. I was happy with the way the phone was setup and did not want to reload all the apps. After trying many things over the phone he convinced me to do the full reset. I did and it was of no help as I expected. He then suggested I send the phone in for repair. I was not too keen on that idea either.
I read the link from wjbBlaster who used a magnet to free up the sensor and I thought why not. So I tried it and I was able to get the sensor freed up and almost working perfectly but still a little erratic. But at least it was functioning. It was working well enough so I didnít go any further.
I needed to use DishPointerPro to align a DirecTV dish over the past weekend and realized my compass function was not working again. I attempted to use the magnet procedure again I was able to get the compass to function but it was very erratic.
It then occurred to me that the phone may have become slightly magnetized. I proved this by bringing a normal fluid compass close to the phone and it spun and pointed at the phone as if the phone was magnetized. I thought why not try degaussing the phone. I built a simple degaussing coil and tried it. After rebooting the phone the compass is functioning better then I can remember. The compass is very steady and works just like the one in my HTC Incredible. After degaussing the fluid compass only changes slightly when the phone is brought close to it.
The coil is simple to build. I took a small box about 1.5Ē X 3.5 and wound the coil around it. I used a small insulated wire about #26AWG. Just about any wire could be used as long as it is insulated. I wound 125 turns around the box and ended up with about 4 ohms of resistance. I secured the turns with tie-wraps in several locations. I connected it to a 12volt AC transformer. It must be AC this is very important as DC would make the coil an electro magnet and not a degaussing coil. With the coil energized I set the phone on it for about 30 seconds the slowly pulled the phone away from the coil leaving the coil energized. Remember to shut off the power soon after. In my case the coil was beginning to get warm. The phone required a power down and reboot but not a full reset. It may require the phone be pulled through the center of the coil for maximum effect. So build your coil large enough to allow the phone to be passed through the center. Remember to have the phone several feet away before turning on or off the power to the coil. Turning off the power while the phone is still in its field can cause the phone to become magnetized. The coil will draw about 3A so be sure your transformer can handle the power.
DO NOT plug the coil directly into a wall outlet. You must use a step down transformer 12 to 15 volts should be fine. It is not critical. You can not use a DC wall wart power supply. The output must be AC.
I do fully believe the phone was magnetized and I will not be using any case with a magnet catch any longer. Only time will tell. What I think is happening is some metal component in the phone is getting magnetized by the magnet in the case cover. From what I have read some sensors cannot be magnetized some can but all can be overloaded by a magnet in close proximity. Some sensors even have built in degauss circuits most low cost sensors do not. Degaussing will demagnetize whatever has become magnetized without damage to the phones other components. I degaussed the phone with the power on and watched the sensor reading during the process. I did not remove the sim card. I did not incur any problems or damage. However, I cannot guarantee my results, proceed with caution.
It would be nice to know if other people that are having compass problem and possibly tilt problems are using cases with magnets. Or perhaps a mobile mounting bracket with a magnet.
If all this turns out to be true I hope the Motorola engineers are able to locate whatever component is becoming magnetized and replace it with a non-ferrous material to eliminate this problem.
Sorry for the long post, ~ Bill
*Special thanks to wjbBlaster who posted the fix with the magnet on the Motorola site. It got me thinking.
*There are several people selling degausser wands on eBay that plug into the wall that should work.
*You might stop by a TV repair shop and have the tech degauss your phone. Most shops should have a coil for degaussing old TV sets.