I have a N900 that will no longer establish normal USB communications.
If you would like to read all about my attempts at a standard reflash read here http://talk.maemo.org/showthread.php?t=84388
To say it short the flash mode using USB was always tricky on the used phone, the USB port is physicaly fine, I had to do a reboot in data mode trick to get the phone to flash and the after a few tries the combined image finally transfered to 43%, without a reboot I dont have the trick I used to get the flash mode to work, now I get a USB device connect and instant disconnect.

If the N900 is bricked enough to not negotiate a proper USB interface is it possible to jtag or use another method with the gold test points in the back of the phone to at least reflash the bootloader so I can get a USB port?

this is /var/log/syslog
Jun 13 11:07:55 laptop-AO722 kernel: [ 345.284364] usb 1-3: new high-speed USB device number 4 using ehci_hcd
Jun 13 11:07:55 laptop-AO722 kernel: [ 345.417049] usb 1-3: unable to get BOS descriptor
Jun 13 11:07:55 laptop-AO722 mtp-probe: checking bus 1, device 4: "/sys/devices/pci0000:00/0000:00:12.2/usb1/1-3"
Jun 13 11:07:55 laptop-AO722 mtp-probe: bus: 1, device: 4 was not an MTP device
Jun 13 11:07:55 laptop-AO722 kernel: [ 345.719001] usb 1-3: USB disconnect, device number 4