Hi DOF
I've never had a Garmin 89, but it should still work fine.
If it has sat on a shelf for years though, it will need a long time switched on with a good view of the sky to refresh it's ephemeral memory. (Where to look for the satelites) This is downloaded from the satelites themselves, so, as long as at least one of the satelites of which previously knew is still in use, and visible it should eventually reload the data. Old units had sequential receivers (Can only listen for one satelite at a time) so these can take quite a long while, first to find a satelite, then to download the data. It will show the 'Searching the sky' caption for a lot of this time.
I revive my old Garmin (55!) by leaving it switched on in the car with an external roof antenna for a couple of days. This usually works.
The ephemeral memory is kept alive in some receivers whilst the unit is switched off by a little hearing aid battery, and you might have to replace this too, if the unit revives it's memory and starts working, only to fail again the first time it is switched off.
Good luck
MJ
