My student's ti nspire won't turn on. They have the 84 face plate on it.
Hello,  
  
Put in new batteries and try again.  
  
If new batteries did not solve the problem, the next thing to check would be the battery terminal.  
  
If
 the battery terminal is rusty, the battery power won't contact and the 
calculator won't turn on. So, use a flat small screw drive to scratch 
the battery terminal so that there would be contact.  
  
If the above
 is not the problem, the next to check would be the wire connecting the 
battery terminal to the the calculator's main board. There is a wire 
between the battery terminal and the calculator board. When the battery 
is inserted, the power from the battery goes from the terminal to the 
board through this wire. There is a possibility that this wire is cut 
in-between or is loosing contact. In this case, you need to get a small 
screw driver and carefully disassemble the calculator in order to check 
the wire.  
  
If the wire is intact, use a light brush to brush the calculator board as there might be dust on the board.  
  
If non of the above helps, then it means the calculator is dead and needs a replacement.  
  
Regards.
if it doesn't turn over... it can not start!!... do you mean it cranks ok .. but will not start? hi @robertjeff,

 

the feature may be turned off. you will find instructions here on how to turn it on. 

 

-attu-versecare brother, you better get a manual. i think they teach a course in this at the local community college. seriously, i can't responsibly explain the procedure to you in a venue like this.
try this link: 
http://bit.ly/mitchell\_repair\_manuals\_online please delete the app and reinstall! it should work timgoos,there seem to be a few threads about this issue. most people, at least those who bothered to respond back to this forum, seem to indicate that turning off the "lock screen controls" resolved the issue for them. my guess is that there's a bug somewhere in the app, and they haven't either figured it out, or looked at it. i'd suggest that you go to settings -> sonos -> lock screen controls and make sure it isn't green (on). it's inconvenient, if you're accustomed to using the lock screen like i am, but then again if it doesn't kill the battery, that's a plus.and if you'd be so kind as to come back and post here to let us know if it works for you, it might help the next person who may be in your shoes.thanks! okay, i think i found out what is happening: <https://github.com/drtimothyaldendavis/suitesparse/issues/45> the otg port does not support isochronous mode when in device mode. In the middle of the TT youll Find a C-Clip It needs to be Removed before the Platter can be removed,You either have a Broken Belt,Or the Grease in the Guide is Old and must be Cleaned out and Relubed pat, sorry to read about your notebook issue.  be assured that i have been monitoring this post and see that you have received very helpful input.  if you're not able to duplicate the memtest86 hit, you may want to scan for "infections" as andre s. recommends.  however, along with malwarebytes, i would also run tdsskiller and combofix.   after doing this and the laptop still freezes, you may want to contact hp's excellent elite premier support team at 866 625-1175, especially if this model is still under warranty.  you also may want to pm me with the product number, serial number so i can get a case started for you or so we can discuss some hp options if out of warranty. problem is a bad capacitor on the power board. caution if repairing yourself as capacitors in tv's hold a charge long after set is powered off and can be lethal. 
  
 when looking at your power board for a bad cap look at the top of the capacitors. a bad cap will have a noticable "bulging" on the top of it compared to others. be sure to note polarity of capacitor (will have a "-" on one side indicating negative. to fix on/off issue simply unsoldered bad capacitor and solder in a new one with same voltage and capacitance rating being sure the new capacitor is oriented the same as the old one was before it was removed.