mobile

Hi,
I've recently had some problems with my device's speaker and after many hours on the phone with htc support, they were willing to send me a replacement phone, however, they only had the at&t model
This model came with bloatware, some at&t graphics on the back, some at&t branding on start, etc. Most importantly, it came without lollipop :(

I'd like to change it so that it behaves like the original htc version that I had, but I don't want to have to upgrade it myself every time an upgrade is available, is that possible? am I voiding warranties when I do that, will it behave exactly like an original htc version?

If so, can you direct me to instructions I can follow to do that?

Thanks,
Elad.