How can I revive my TI89 after two years of not using it?

assuming you tried replacing batteries could you have some put in backwards? if not all of them

Having received no response in half a year, I assume my suggested reset solved the problem.

TI calculators have an annoying habit of dimming the screen when the batteries are changed so that it appears as if the calculator isn't turning on. Turn the calculator on (or at least press the ON key). Press and release the 2ND key. Press and hold the Up-arrow key for a few seconds and see whether the screen becomes legible.

If you open the CATALOG of commands, you will not find a DiagnosticOn command. It does not exist for the TI89 because whenever R and R2 correlation coefficients are meaningful they are calculated by default and displayed on the screen where you get the regression equation. If they are not defined bu the statistical theory no R or R2 are calculated.

In short You do not need a DiagnosticOn command to have R and R2 calculated. If the regression model uses them, they will be calculated by default.
By the way, DiagnosticOn is a command for the TI83/83Plus/84Plus but not for the TI89/89Titanium/92/92PLUS/Voyage 200PLT.

Hi,
The calculator must have a backup battery in. It will supply energy to the memory module when calculator is turned off. You may lose the content of the memory.
I do not want to sound dramatic, but you may lose the OS and you would have to reinstall it. Put fresh batteries and see if your calculator is still operable.

Hope it helps.

Hello,
The answer I gave you was taken verbatim from the TI FAQ and knowledge base. I copied and pasted the part relevant to you calculator.
In any case, I sent an e-mail message to [email protected], giving the link to your original question and my answer to it. I took the liberty to copy/paste your present message. I also asked about that invalid certificate.
All we can do know is wait for their reply.

k24674.

you need to replace all the battery leads in there but yes you can revive this just do to radio shack and by the battery leads pop open that device and solder the new leads in.. if you do not know how to solder then it can get trickey..

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/edwy_1a56970cf1ea4620

The TI-89 has one function to find whatever root you want of a number.

To find the cubed root of say...64, you would type:

root(64,3)

I had mine for 15 years. Are the batteries in correct? Might be broke

SEND IT INTO Ti, LET THEM CECK IT OUT, FOR A SMALL FEE IT'S WELL WORTH IT.
IT'S BETTER THAN BUYING A NEW ONE, PLUS THAY WILL
FIND THE PROBLEM AND INTSTALL THE LATEST VERSION SOFTWARE IF NEEDED TO BRING IT UP TO LATEST CONFIG, AS THAY DID TO MINE.