Disconnect the blue wire from terminal 2 and try again. You could also try connecting the red to T2 (leave blue disconnected) as that is what the Honeywell instructions show. T1 bypasses the switch; T2 goes via the switch.
If either of these stops the fuse blowing, there must be a problem inside the stat and it will be safe to change it for the Digistat. If it doesn't, we'll have to dig deeper.
PS I was wrong about the T6360C intended for aircon; it's the T4360C which does that.
Your suggestion about disconnecting the Stat and joining red to yellow is a good idea, but do it only if my tests above fail.
If either of these stops the fuse blowing, there must be a problem inside the stat and it will be safe to change it for the Digistat. If it doesn't, we'll have to dig deeper.
PS I was wrong about the T6360C intended for aircon; it's the T4360C which does that.
Your suggestion about disconnecting the Stat and joining red to yellow is a good idea, but do it only if my tests above fail.