"The on/ off switch is a touch sensitive"
Are you sure about that? Usually this would be a membrane switch, a physical switch with a plastic "bubble" on top but still a physical switch inside. They rarely corrode and usually can't be cleaned. If it is a carbon-button contact, like many remote
controls and phones use, sometimes you can use alcohol to clean the contacts, the keypad plastics leach out a non-conductive gunk as they age. But true touch-sensitive with no moving parts
? There's nothing to fix if that's it. If the unit won't power up at all, there may also be an internal backup battery
which has died and needs to be replaced.
More likely the coax is damaged, or rain got into the antenna and ruined it.