The only way to really undo the damage done by sitting in funny positions is, well, to do something about your posture. This strain occurs when you “hunch forwards over the computer or laptop”.

Check if the computer boots successfully to confirm ... to ensure you don't end up forcing the processor to sit on the socket ...

Cornell University ergonomics professor Dr Alan Hedge sets out why the 90° rule does more damage than good, and what the proper way to sit at your desk is.