Well, what can I say, de ja vu, was it a heater malfunction or just ambient room temperature? I wouldn't hold out too much hope for the 3 survivors either if my experience was anything to go by - but I will keep my fingers crossed they survive!
Really sorry to hear the news and if anyone can feel your pain that would be me. Hopefully you can just remove the cooked shrimps and start again without having to go through the whole process of re-setting up the tank and cycling from scratch like I am?
Hope everything is going well with the old tank.
The shops sound similar to ours in old towns, they started as houses and then get divided to shops street level and basement and the upper floors are either offices or residential.
update, some upsetting new, all shrimps except 3 has died in the new tank, as the water in the tank went upto 31 celcius, the other 3 was half dying, I put them into the old tank, and seem to be ok for now.