Ride on mower troubles

[Olderisbetter]

My uncle has a Titan TTK550lwm ride on mower which is sold by screwfix but is the same as a Mountfield 827M or R27M so we thought it should be OK, It has been used about 20 times in 4 or 5 years and stored indoors, It was used a few months ago and ran fine but when we tried it 2 weeks ago it was clicking like it had a flat battery so i put another one on and it had the same problem, We have ruled out the battery and if we put a wire to the solenoid + side it wings over like it wants to start but off the key it really struggles. any ideas or anyone had the same fault?
Things we have tried so far..
Changed the main fuse
Fresh fuel
tested it has a good spark and is not seized
it is getting fuel through and even tried easy start
tested the limit switches circuit
tested the ignition switch
took the top of the engine and flywheel out to check wiring and spark thingy
found an "ECU" and tested the relays and fuse on it looked for any damage or issues and a replacement is £85 for what looks like £4 worth of bits.

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[m_c]

Probably a safety switch playing up.

 

[mike 109444]

If you have spark. Dribble a little fuel down the spark plug hole and refit plug, see then if it fires up.
Some have a decompression valve for ease of cranking.
Check out mustie 1 on Youtube. Nice intresting guy to watch and should have done a machine much like yours.

 

[badabec]

Probably a safety switch playing up.

Yes, the times that has caught me out. Now I bridge the switch connector with a piece of wire, although one time I bridged the switch side and not the feed!