Ordinarily, the I/O annunciator is on only when the calculator is actually sending or receiving data. One bit in System RAM normally controls whether any particular annunciator is on or off. I'd expect that transferring some data should force it to the correct state, but perhaps the calculator is still trying to send something. Even so, I'd expect any transfer to eventually (within a minute) time-out.
An exception to the time-out would be using a "Serial I/O" command after executing 0 STIME. Maybe try forcing the time-out to its default value of 10 seconds by executing 10 STIME.
I'd try the CLOSEIO command, although I'd expect that turning the calculator off and then back on should've aborted any transfer and closed the I/O port.
You could try forcing a warmstart by holding down ON, pressing and releasing C, and then releasing ON.
If all else fails, you could try archiving everything to a PC (don't forget to also transfer anything that you want to save from port 0) and then forcing a TTRM (Try To Recover Memory?) by holding down ON, then A, and then F, and releasing them in reverse order. I'd first try answering YES and let it try to recover memory, and if that doesn't help, then NO to let it erase everything and restore everything in RAM to its default state. After clearing memory, you can use the RESTORE command with your archive file to get things back to normal.
But what I really expect is that your 48G+ has a hardware failure, and if none of the above helps, then it's probably best to just live with it.
Note that if for some reason the I/O port is staying open, then you can expect a higher than normal drain on the battery.
Regards,
James
