HTC ONE last update. Bootloader claims tampered I have an HTC One bought unlocked (i.e. no simcard) with Android. I swear on my grandma's tomb that I've never tried to tamper it (I don't even know what that exactly is, I thought that made only in very closed phones such as iPhone). It was updated to the last version until a couple of days ago I got a notification to install the last update. After downloading and clicking in install it reboots the phone and I come to a bootloader which says

tampered
locked
security warning


some other data and gives me usual options for reset. I have read online that this happens when one 'tampers' the phone, which I haven't. There are solutions to 'untamper' it online, but I am afraid that attempting any of those solutions

As a side note: the phone was bought from HTC's US website less than a year ago, so it must still have the warranty running but I am not sure if I should contact them (I fear they say the warranty is invalid if the phone says tampered).

I believe all the apps were installed from the Google App Store. I installed F-Droid because a friend recommended it, but I never used it.

Any idea on how to get rid of this silly message, keep my phone under warranty and install the update?
Go to the HTC site and download the official ruu file for the HTC one and run it. There should be an explanation on htc's site or you could ask them to walk you through it. This will fix the security bootloader thing and update your phone.