In this video I replace a toilet flush mechanism with a Jollytronic, electronic flush valve. These are very easy to fit and can be installed in a couple of hours. As well as fitting the Flush valve, the fill valve also needs changing, which in most cases is relatively straight forwards. The Jollyfill was supplied with the Jollytronic kit. The electronic sensor will fit any hole from 38mm to 45mm in diameter. I do not know how reliable this will be, so I will post back in future, if it is not reliable.
You can buy the valve kit for about £60 from eBay- https://fave.co/3tVvr0W
Or Amazon - https://fave.co/3d3MgQm
You can also get them at most plumbers merchants
How to fix a leaking stop tap- https://www.youtube.com/watch?v=BPc3Y4xavts
How to replace a toilet syphon - https://www.youtube.com/watch?v=y4AdckesOlg&t
How to make the cover plate can be seen here- https://www.youtube.com/watch?v=ltyG9kXCRsw