You’ll be lucky to find a manual.
Push the carriage upwards until the chain goes slack, disconnect the power.
Open the downside panel and disconnect the long plug and earthing which connects to the seat, remove the seat cover panels, pull the wiring out, undo the two 13mm T bolts and the lower allen bolt and the seat will come away from the carriage.
Remove the top track cover, undo the two fixing bolts and pull out the wiring connectors and remove the pulley wheel from the track, tease the grey flat cable out of where you have just pulled the wiring connectors and drag out the counterwieght from inside the track.
Cut off all the cables and then pop the chain off of its fixing and remove the L bracket at the top of the track, hand wing some of the chain through to below the lift to remove chain tension. Find a removable link and disconnect the chain below the carriage. The carriage can then be pushed off of the top of the rail. If you’ve got that far you should be able to work out the rest.