Question about unrooting and locking bootloader

[shanimal92]

i have the worst signal, so if they dont fix it soon i am going to take it back. I know i can unroot and relock the bootloader but will it delete everything off the phone? or will it just back it so i cant do "root stuff," and not change anythign else? also, say i wait like a month to give the time to fix it, so its waayyy outside my return period, will i ahve to pay the premium if i take it back and it needs to be returned even though its not my fault its screwy?