Please help me revive this sick m7

Hi Guys,

Bought an m7 cheap on ebay. I don't know anything about the history, except to say it's been fiddled with...

It powers up but it won't boot up; it hangs on the HTC logo.

Bootloader's unlocked, it's been rooted... S-ON

(bootloader) version: 0.5
(bootloader) version-bootloader: 1.57.0000
(bootloader) version-baseband: 4A.21.3263.04
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main:
(bootloader) version-misc: PVT SHIP S-ON
(bootloader) serialno: ** edited out **
(bootloader) imei: ** edited out **
(bootloader) meid: 00000000000000
(bootloader) product: m7_ul
(bootloader) platform: HBOOT-8064
(bootloader) modelid: PN0710000
(bootloader) cidnum: 11111111
(bootloader) battery-status: good
(bootloader) battery-voltage: 4297mV
(bootloader) partition-layout: Generic
(bootloader) security: on
(bootloader) build-mode: SHIP
(bootloader) boot-mode: FASTBOOT
(bootloader) commitno-bootloader: dirty-e47fb74b
(bootloader) hbootpreupdate: 11
(bootloader) gencheckpt: 0

I'm thinking I should try and take it back to stock, but I don't know where I should go from here and I'm worried I might screw it up.

Any help would be greatly appreciated :)

Thanks in advance!