Help Installing Os / Reinstalling Os. :(

Okay some how some way I kinda forgot, but now my calculator says, "Waiting... Please install operating system now". I plugged it into my computer used TI Connect/OS Download, and it starts downloading but once it reaches 100% it says, "ERROR! Press any key to turn unit off. Then turn unit back on". I have no idea what to do and have been searching google for hours. Please help you're my only hope. Also I have a math final next week. >_< I have a second one but it's a ti 84 Plus C.

 

It's a calculator. A Texas Instrument though he never specifies the model of the unit he is having trouble with. He has a working TI 84 Plus C.

I own a TI but it is from the era before calculators connected to computers.
To offer any help you need to post the exact model and also why you connected it to your computer. https://education.ti.com/en/us/products

 

Fixed it. Emailed TI Support this is the solution I used, "
One solution is to apply a fix to update OS Downloader. Updating a TI-84 Plus Silver Edition Graphing Calculator manufactured after 2011 with an older operating system can cause the calculator to lose that operating system. To correct this problem, follow the steps found here:
http://epsstore.ti.com/OA_HTML/csksxvm.jsp?nSetNumber=34451". Thanks anyway.