Mercury 25hp won't fire

[PatricsOnTheCoast]

Hey guys,

Have my outboard at the mechanics and they fixed what we thought was just an electrical issue with the trigger assembly (all brand new) but it still won't kick over... They have tried fuel in the cylinders and all but nothing seems to be happening save a little back firing.
Anyone have any ideas what could be the most likely cause? They have stopped work on it until we decide weather its worth opening up and finding the cause (the expensive part)
Would anyone know any likely causes for this?

The motor is a Mercury 25hp 1996
Serial: 06309104
Model Description: 25M
Rev Limit: 6000rpm
HP: 25
LB 115

[Gon Fishun]

Pressure test it for crankcase leakage and or no pressure. Maybe popped a crankshaft seal.

[Steeler]

I take it a compression and spark test has been done ?.

[finga]

The 3 things you need for a 2 stroke. Spark. Compression and fuel.
You've ruled out fuel.
Is there spark?
If they suspected spark before then maybe spark is still the cause.
Is there good spark? If not try bypassing the kill switch.

Personally I'd be changing mechanics too.

[PatricsOnTheCoast]

Plenty of spark they assure me, which doesn't fill me with much confidence about the compression... We will do a compression test on Monday if he hasn't already done one. I would have assumed he would have done something like that already but he hasn't made mention.

Sigh fingers crossed.