My sleep/lock button doesn't work.

I have to admit I'm guessing. But pretty sure those buttons are soldered onto the board. So it's not the tangible button you touch. You can download an app that does power button functions. Like this guy said. Or it's microsoldering. I can't imagine that phone costs very much

I have the same problem. I found i way to turn boot the phone still though. I just have to stick a pin or similar thing in a little space in the back of the phone and hold it there for about 3 seconds and the phone will be booted. To wake the screen i just downloaded an app where i can use the power button to wake it and also downloaded an app where i can use the sensor beside to front camera to wake it.