Why is my Lumia 520 continuously rebooting?

[ganga rapu]

my lumia 520 is continously rebooting

iam using lumia 520 10166 build and my phone is continously restarting "i have performed hard reset and normal reset in the phone even though the spinning gears were not coming"plz respond urgently

 

[Laura Knotek]

Re: my lumia 520 is continously rebooting

I'd recommend using the Windows Phone Recovery Tool to roll back to Windows Phone 8.1. https://www.windowsphone.com/en-US/how-to/wp8/phones-and-hardware/recover-my-phone

 

[HidingTrouble]

Re: my lumia 520 is continously rebooting

I had the same problem with my 920. I tried the recovery tool but it kept rebooting while it was trying to roll back to 8.1 so it never took and I just gave up, but that's not to say you shouldn't try.