HTC Hero :: Managed To Get 3G Data Working For Weather Email However Browser Does Not Work

I just bought a Telus HTC Hero, which the seller had unlocked. I intend to use this phone with another carrier, Bell. After spending a few hours at Bell customer service, they finally managed to get the 3G data working (for weather, email etc.). However, the browser does not work, neither does the Market.

What seems to be causing the problem is that this phone is MASSIVELY tweaked (appears massive to me probably because I'm not that big on tweaking and don't know about the Android OS in general) by the previous owner who only had it for a few days. The Bell customer service person told me that they switched over a couple of other HTC devices from Telus that were NOT tweaked and the data works perfectly.

All I want is for the phone to be in original factory settings, with original ROMs, firmwares, software, etc. etc. Just looking at the whole bunch of different files that this guy had on the 2GB "gold" memory card made my head spin. He attempted to explain to me with all the "updates" and fancy "roms" and "roots" and crap that I didn't understand nor do I want to spend the time to learn.

I understand that a lot of people buy android phones because they love tweaking but I am not really into all that... I just wanted the phone for the form factor and the functionality and I don't want to worry about optimizing and whatnot. So my question is: is there any way to get the phone back to the most original possible software condition? I just want it "clean." Can I go ahead and wipe everything that is on the 2 GB card? What do I do? I performed a hard reset and it took me to some weird startup screen and I chose the first option which is like reboot now (there were also a bunch of other options including apply update.zip or something)... it still gave me the same MoDaCo build.

I can provide any information but I would really appreciate any help in restoring my seemingly very tweaked phone to original, factory settings, so it could be like any other phone being sold by Telus other than the fact that it is unlocked.