Root [T-Mobile] [Unlocked] Boot Loop?

[Zhfid]

Hey all

My phone randomly rebooted after charging over night
Now it's stuck in a "boot loop": HTC screen > reboot > HTC screen > reboot, etc

I can access the Fastboot menu (power+vol down) but if I choose Factory Reset or Recovery it goes into the boot loop again

It's been Unlocked with S-ON since last year without any problems, though I never got round to installing a custom ROM (I use stock)

fastboot getvar all:

(bootloader) version: 0.5
(bootloader) version-bootloader: 1.57.0000
(bootloader) version-baseband: 4T.29.3218.08
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main: 6.09.401.11
(bootloader) version-misc: PVT SHIP S-ON
(bootloader) meid: 00000000000000
(bootloader) product: m7_ul
(bootloader) platform: HBOOT-8064
(bootloader) modelid: PN0710000
(bootloader) cidnum: HTC__001
(bootloader) battery-status: good
(bootloader) battery-voltage: 4262mV
(bootloader) partition-layout: Generic
(bootloader) security: on
(bootloader) build-mode: SHIP
(bootloader) boot-mode: FASTBOOT
(bootloader) commitno-bootloader: dirty-6d8a0b9b
(bootloader) hbootpreupdate: 11
(bootloader) gencheckpt: 0
all: Done!
finished. total time: 0.042s

What's going on?
Any ideas how I can fix it?

Thanks!