There are some funny race conditions around hardware keys and touchscreen locking
- once the cursor keys were inverted (left to right, up to down), I had to rotate the screen up to down and then back to normal to get them working right
- sometimes it says I have to press the key to unlock but the touchscreen is not locked
- sometimes the touchscreen is locked but not the keys
Unrelated, may be already not relevant, on monday I've seen abnormally high battery comsumption with 0.5.2, about 0.8%/hour, with the device completely idle. It hasn't repeated again with 0.5.3, so may be you fixed the cause, or it is another race condition.