Laptop Li-ion battery repair isn't really an option because reseting the
contoller inside the battery just isn't possible. Given the price of a
new battery is prohibitive and, if it's an older laptop that one doesn't
want to replace, availability of batteries, especially given their 3-5 year
shelf life, is also a problem even if one were prepared to pay the asking
price.

Other than running with a dead battery or removing the battery, are there
any other options for restoring some sort of operation remote from the
mains?

Many thanks.

Martin