Does SEUS perform a full flash?

HI, my phone died and went to the service center about a week ago. I kinda regret that I sent it in, since it was a K750i flashed to W800i with some extra patches applied.
I think it's the FS that's broken, but I either way reflashed the MAIN with my patched W800i firmware in hope of reviving my phone. It didn't work (it did flash, but still dead phone). So i plugged it in and asked SEUS to update my phone in hope of it to fix and flash it back into a normal K750i again.
However, I asked on another forum if they would find out that my phone had been modified, and this guy said to me that SEUS doesn't necessarily flash the whole MAIN, just changes what's necessary and leaves the rest untouched. Thus leaving it with still some parts of the modified W800i firmware inside.
So I wonder if it's true that it doesn't flash the whole MAIN, just changes some here and there and leaves the rest untouched?
Cause in so case, they'll find parts of the W800i firmware inside.

AFAIK, SEUS does a full MAIN flash + some parts of the FS. Wouldn't it be easier if you did a full flash with k750's firmware (MAIN+FS) yourself?

I don't think they will look for software modification traces, I don't think they have time for that. I think if they see the phone doesn't work they will try a full reflash, EROM, GDFS or else. Please tell us if they said anything! :)

Yeah, in aftertime I've come to the conclusion that it must've been the FS that was broken and that I should've just flashed that part as well.
But I was kinda desperate and I sort of couldn't explain to everyone that it might've been my fault.
Either way, the firmware is back to K750i R1DB001 and the FS was never actually flashed to a W800i due to an error. Whatever they might find not suited for my phone (W800i content) will be erased when they flash the FS as well. So no traces left of my modding (hopefully).
I really hope they don't find anything, cause it said somewhere in the contract I signed that they can charge me for about 75$ if they find out it's my fault it's broken.

try to be more careful next time

Woot, I got my phone back today.
It's been 2 weeks without it now, but damn I'm glad to have it back.
I think they just did a full reflash of the FS and MAIN, so all my things are gone. And they didn't seem to charge me for anything, which makes me a happy person :D