[VivekRabara]

I don't know why but now a days my Lumia 520 restarts automatically and it drops percentage of battery to very low level. Sometimes i also noticed that power button stuck sometimes. Does the restart problem occurs due to battery related problems or what? Does anyone else facing the same problem?

[gpobernardo]

Looks like a hardware button-related problem, specifically the power button being stuck at times. Notice anything else that is unusual with the power button? Does the power button spring back normally? Do you feel the "resistance" of the button when pressing it, or does it just get pressed almost with no effort?

[VivekRabara]

Does the power button spring back normally? Do you feel the "resistance" of the button when pressing it?

Yes i am feeling the same, but what about auto restart? Is it battery related problem?

[gpobernardo]

Yes i am feeling the same, but what about auto restart? Is it battery related problem?

Does it really restart the normal way* or does it suddenly turn off and then turn on on its own? If you see the "Good Bye" message first before it turns off, then most probably you have a defective (might be dusty or shorted inside) power button. But if your phone just turns off on its own, then there might be a problem with the contacts of the battery, as seen in this thread. Other L520 users experiencing the same problem have suspected a loose battery, so they tried inserting a piece of paper in the battery compartment to tighten the space between the contacts, while some have tried bending the contacts so that the battery isn't loose... and they no longer experienced the problem.

*- You should see the "Good Bye" message in a normal restart.

[VivekRabara]

I am not getting good bye message. So may be problem related to battery, will check the given solution and post the response here.

[VivekRabara]

Looks like solution has worked. Not restarted till now. Hope it continues the same way. :)