The other day I wanted to listen to some music on my walk with my daughter. I pulled up Slacker and it asked to be upgaded to tthe new version. I pressed ok. It downloaded and then asked to be reset. I pushed ok. Bad idea! I had the newest OS on the 9000. It reset, again and again. I got home hooked it up to the newest version of the Desktop Manager. wiped the memery and had it reinstall the OS. It shut off before it finished, the D.M. said there was a fatal error. The phone, when the screen briefly appears, it says reload software 507. I've tried to reload it more than 10 times for the past two days. No avail.
Any ideas on what I can do. I live with this thing on my hip or in my hand about 20 hours a day and I'm lost without it. like today when I wanted to convert mm to SAE at work (14mm roughly 9/16.)

What happens when you try and turn on the phone? Also, take out the battery, then put it back again. When reinstalling the os, rather than using DM, use loader.exe.

Can't turn it on. It cycles through resetting itself over and over, red LED comes on, then white screen with clock and then the error 503 pops up. Shuts off and then the red LED white screen... Same happens after removing and reinstalling the battery 'till it dead. The DM is the only thing that actually can stop the resetting cycle for a while, until it turns the phone on to download the OS. Then the DM prompts a fatal error as the phone shuts off and resets.

Did you try reinstalling the os using loader.exe?