Well, the card is not bricked, but the S1 didn't make proper contact with the GPU. I put the stock cooler back and, surprise... it worked.
I replaced the preapplied MX-2 with a rather thick layer of Tuniq TX-2 and then mounted back the S1, squeezing the screws to maximum.
The temps I'm getting with a fan on the S1 are ~5C worse than with the stock cooler, and in Furmark it shot to 95+ in a couple of minutes.
But the fins of the S1 didn't get hotter than about 50C, I was expecting to be unable to keep a finger on them.
So I believe that the S1 still doesn't make proper contact with the GPU. The TX-2 layer stayed thick after installation, not much of it was pushed sideways.
I think the clear spacers of the S1 are a bit too tall. Or the 5770 GPU (on this card only?) is too low relatively to the PCB.
You may want to try again with thinner spacers, that's what I did. My first S1 attempt was even worse than yours: 15+ on idle and a whopping 110C during a really stupid Furmark test. The card seemed to still be working fine though, and I let it cool for some minutes before shutting down to put a fan on. The next couple of starts showed no picture in Windows though, only in safe mode, which had me worried for a while. After taking the card apart, replacing the spacers, bending the bracket back some, cleaning the base and applying a thin
layer of AS5 it worked fine though. Fanless the temps are worse than the loud stock fan, but that's natural. With a quiet fan they are better.
Anyway, right now I'm sorry for buying it. My 4850 + S1 idles at 38C and only reaches 53C in Furmark, with a 120 mm Slipstream fan at 600-750 rpm.
Sounds like an efficient 4850, or maybe just very good contact with the S1.
PS. For comparison, I checked the S1 fins' temperatures' when idle and in Furmark, mounted on my 4850, and they are quite low.
I correct my previous statement , that the S1 doesn't make good contact with the 5770 GPU, the S1 fins are significantly hotter on 5770 than on 4850.
Which makes me believe that this 5770 - that I may have damaged - is now drawing more power than my 4850, so it's a nono.
Especially strange if the card is drawing more than before. Test the power consumption if you can. Mine increases about 100W over idle with Furmark 1.8.0, a little more than expected but part of that may be the CPU.
Btw, from the pictures I can't tell the distance between the mounting holes. If they are 42mm you may need to cut the corners on the mounting bracket.