Htc one M9 stuck in bootloader

Hi,

My one year old htc one M9 used to work fine, until a day when it discharged and went off (because of no charge). I recharged turned it on but it ended up stuck on the htc start up logo. I thought it was a hardware issue so I took it to a technician who tried to flush but they couldnt get it working. Instead the phone now starts up to the bootloader with these infos:

*******Software status: Modified******

• LOCKED*******
  • S-ON*******

*******Security Warning*******

<vol up> .......

<vol down> ...

<power>....

REBOOT

REBOOT TO BOOTLOADER

REBOOT TO DOWNLOAD MODE

REBOOT TO RECOVERY MODE

POWER DOWN

I have tried to factory reset and stuffs to get the phone back on but nothing worked.

Any ideas? A way to reinstall the whole system may be?

Thanks.