I know its been said in a previous post, but it sure sounds like your keyboard is stuck. Even if the keys don't seem stuck, it doesn't mean it's not electronically stuck (continuity) via the contacts or membrane (i'm not sure what type of buttons are used in it).
If you are able to flash in recovery, or flashing a .sbf seems to work, then it really seems like a hardware problem where your phone is stuck going to the bootloader..... for which there are like 2 ways to get into the bootloader. keyboard combo, or booting up with usb connected to a pc. The phone is going to know the difference if it is connected to a PC or a USB charger by the usb d+ and d- lines, and the state they are in as the phone boots.
I'd try to exchange it.
You're 100% right about the keyboard being stuck. I too just got this problem yesterday. I was trying to put the volume up and it wouldn't go up, so I reset my phone. Next thing you know the bootloader screen pops up. I immediately look up the problem and decide to take it to my local Verizon store.
From there after waiting like half an hour the manager comes up to help me. As she's waiting for one of the employees to finish using an AC Adapter cable, she playing around with my phone and all of the sudden the Motorola logo pops. From there she takes it to that place where they flash phones and as I'm waiting, she comes up to me and tells me that the phone is on and asks me to place the password (I don't think she flashed the phone or anything since I still had all my apps; I think she just somehow got lucky as before when she made the Motorola boot logo pop up). Then as I'm going through my phone, she tries to ask me if I rooted it by saying "Do you have any third-party applications" and I tell her I don't think so and that I'm pretty sure the problem I'm currently experiencing is related to the hardware. So she tells me that they don't have any replacements in the store and that they'll have to order one in the mail which I'll receive this Monday in the mail (3 whole days!).
So I go home, back up my texts, back up my apps and settings via Titanium Backup and think of a way another way to back up my stuff for the new phone (just as precautions). I also tell myself that a Nandroid backup would be perfect but I'm worried that the bootloader screen might pop up again.
So I start to look at my phone and I notice that the up volume button wasn't the only button not working; it turns out that half of the keys on the keyboard aren't working and that included the x button (which I'd need to boot up into SPRecovery), up, down, and ok buttons on the d-pad. So I knew that I would be unable to load up into SPRecovery and I remembered ROM Manager and they option where I can load up into Recovery Mode by just pressing that option. Once I did so and next thing you know the bootloader screen pops up again! So here I am stuck at square one once again.
I tried to just reflash my phone via RSD Lite and make it anew since I'm going to have to unroot sooner or later before I send my old defective phone off once I get my replacement in the mail (and I also needed to have a working phone for until I get the replacement!). But RSD has failed me and gave me an error which didn't surprise me since this has been a hardware problem.
So now I'm not sure what to do. Should I just keep on pressing the power button and hope for the phone to randomly turn on perfectly? Or should I go back to the Verizon store and talk to the nice manager lady to somehow get a replacement now (but I don't want to bother her since I know that she knew my phone was rooted or something was up and she might get annoyed)??
