yeah same thing happened here. was told on the phone today via a tech person at vzw that if they send me a warranty replacement and they find out that i rooted it, then they would automatically charge my account the full retail price of the phone. so i politely told them no thanks haha. but that might be different if you were to go in to an actual vzw store and tell them that you were on ota 2.2, didn't like it, and tried to sbf back to 2.1. from some things i've read, if it's stuck on the "bootloader....MAM_MAP Blank...etc, etc..." then they won't be able to flash it either, and they will never know it was rooted. may want to have that confirmed before you head up to a vzw to attempt to get a new DX. i am still waiting for confirmation on that also, and hoping that a full 2.2 sbf comes to us all quickly!
Curious, did you call a Verizon Store, the main Verizon 800 number, or the Warranty Center ???
FYI, mentioning using a "leaked" SBF might not go over very well... and saying you were trying to reverse their offical update is not a very good argument either... That would be like buying a 2010 Ford, flashing the 2009 version engine computer software, and going in to the dealer saying it won't run anymore and BTW, I "hacked" in the older engine software...fix it for free....on the other hand, they would fix it for you and not charge you for a whole new truck...at most a new engine computer (which would also now have a new warranty) .
I also do not believe that they (Verizon Corporate and/or Warranty Center) would go thru the effort of investigating whether your Droid had been previously Rooted or not... They have better things to do and pretty sure when a return phone comes back in it is gonna be reflashed pretty much the first thing..If I was going to be refurbishing a phone to go back into service ASAP, it is the only way that makes sense to efficiently(and inexpensively) test and verify any hardware issues in the refurbishment process.
IF you take it to a Verizon store and a Tech there is trying to be a jerk or impress his boss..maybe..but I doubt they would have the expertise to prove it to a level that even a Store would try to backbill you for a new phone. I think the only way that would happen (being backbilled) is by not returning a phone after getting a replacement.
Handle how ever you feel best, but I would call the Warranty Center (# is, or was in your contacts) and tell them you had a problem after the 2.2 update..and that it won't boot... I doubt they would quiz you farther. If they do then only you can decide to fess up or play dumb.
Regardless, there should be some way that Verizon would (I know they can) fix a phone for a customer, especially when it is a software issue...even if the customer did something they shouldn't have...without trying or "threatening" to charge full price for fixing/replacing it. Imagine if automotive manufactures tried to do that, they would be out of business. I know it is a big difference, but in spirit it is the same thing.
Funny thing I noticed when shipping back my defective Droid X today (2 actually, 1 M boot issue, and the replacement arrived with a not perfectly level hard buton) ...the return Fedex labels Verizon sent both clearly had a $100 insurance statement on them.
