soft-bricked m7

Hi, well i kinda ruined my m7 after a failed attempt of rooting. I got stuck on bootloop and tried flashing my stock backup but it didnt boot up and i lost the original version. I went to the HTC service booth the other day and the guy said i have to change the motherboard but im kinda broke so I just wanna know if the guy was just tryna make some extra cash or i really did damage my phone and a motherboard swap is necessary (i tried flashing stock firmware but im S-ON and i couldnt find any firmware, ruu or anything really that matches both my MID and CID)

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