Updated my S5 this morning and now it's constantly turning itself on and off and I can't access 3G/4G, send messages, anything.

[barrych2]

Any advice from anyone with the same problem? My phone is completely useless right now.

[stef7]

Yeah, first try a low-level cache clear (instructions in multiple threads on the site, or Google it).

If that doesn't work, backup important personal content and perform a Factory Data Reset.

[barrych2 · Accepted solution]

Thanks for replying! I'd done the cache clear several hours ago and it didn't do anything, but I just took my battery out for an hour and now it works! I was just about to post that it was fixed. Random, but I'm not complaining. Thanks again

[stef7]

Ahh yes, the power down / power cycle trick.

I hope that's all that needs to be done!

Actually, it's not a bad idea once or twice a week to power cycle the device. Removing the battery shouldn't be necessary.