[Q] Need Help with M7 U

Hi Forum,

I'm a little stuck here, and before I break something I just ask for help.

device: HTC One M7 U (not UL!)

software status: I can access bootloader and recovery, the phone is not booting to android


what I want:

1. a working rooted phone
2. that's preferable google free
3. with a fresh system (full replacement, there is a possibility it got compromised by a 3rd party: lost and "found" some time after)

when I start the phone the white "htc quietly brilliant" screen appears with red text at bottom "This build is for...", after 25 seconds the phone reboots into recovery mode

the phone was flashed with a custom mod before

phone got reflashed with a wrong CM version (maybe one for a M7 UL?)

I can't answer questions for the phone/mod history because I'm the new owner (nothing was paid, but not stolen either, so no problem there)
If there is a strong need for on of those questions I can try to get in touch with the old owner.

I have OSX and Windows 7, and can get access to linux machines. I don't compile stuff normally, but can get a build system running (with help of friends) if needed.

hope you can help me

thx

<EDIT>
I tried RUU_M7_U_JB_50_HTC_Europe_1.29.401.2_R_Radio_4A.14.3250.13_10.33.1150.01_release_311663_signed_2_4.exe but failed.
<\EDIT>


specs:

ClockworkMod Recovery v6.0.3.1

bootloader screen:
tampered
unlocked
m7_u pvt ship s-on rh
hboot-1.44.0000
radio-4a.14.3250.13
opendsp-v26.120.274.0202
emmc-boot
may 4 2013,16:21:26:-1


(bootloader) version: 0.5
(bootloader) version-bootloader: 1.44.0000
(bootloader) version-baseband: 4A.14.3250.13
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main: 1.29.401.17
(bootloader) version-misc: PVT SHIP S-ON
(bootloader) serialno: xxxxxxxxxxxxxxx
(bootloader) imei: xxxxxxxxxxxxxxx
(bootloader) meid: 00000000000000
(bootloader) product: m7_u
(bootloader) platform: HBOOT-8064
(bootloader) modelid: PN0711000
(bootloader) cidnum: HTC__M27
(bootloader) battery-status: good
(bootloader) battery-voltage: 4248mV
(bootloader) partition-layout: Generic
(bootloader) security: on
(bootloader) build-mode: SHIP
(bootloader) boot-mode: FASTBOOT

thx, new TWRP helped a lot, I've just flashed a CM 10.2.1 to see if its working


now my question is:

How do I really clean the phone?

there is so much info out there, but either its too special without explanations or something different to what I need


Is there a way to delete everything (except bootloader) and make it new? (like formatting the partitions on a PC)