Long roofing repair video from taking the concrete roofing tile up – repairing the underlayment – installing battens – then roofing tile.
No rotten wood in this video – the problem in this case was the fasteners and the battens.

Start – Remove Tile
17:33 – final clean up after removing tile
18:13 – installing underlayment patch
30:00 – sealing edges of modified patch
41:13 – Installing new battens
45:26 – Installing tile
54:27 – Installing last row of tile