The first of Lisa's two computers -- the one that was severely damaged but which I thought might be repairable -- is now officially a write-off. Turns out the system board was damaged. Had it been intact, it would have been just barely feasible to rebuild the machine. As it is, when you add in $600 to replace it, the cost becomes uneconomic. I guess we'll just salvage those parts that are reusable and working like the battery, CD-ROM, and memory chips, and move onward.
Next job is to contact Dell about the second computer, which is covered by a service contract, and get them to fix the wonky hard drive connection.