OK, from screen blinking/turning off I concluded that my calc is crazy.
* The contrast is suddenly much lower.
* Only button that makes the screen blink/turn off is the DEL key.
* If I insert the battery with no buttons pressed, DEL key turns off the screen after it's released. No other buttons will do it. When trying to flash OS in this mode, TiLP gives the "not connected/timeout" error.
* If I insert the battery with DEL button pressed, DEL keys turns off the screen after it's released. No other buttons will do it. When trying to flash OS in this mode, TiLP gives "error writing to device/device not functioning error" which happens much faster after clicking "Forward" button in OS flash window than the delayed timeout message.

Is your warranty still valid?

But would it be due to corrupted flash or would it be due to hardware issue? Anyway I hope you still have the receipt and that the warranty is still valid.

Ah ok thanks for the info. I was wondering since the black screen seems like a rather common problem on that model.

Ok, so an easy way to determine what the calculator is doing when the screen is off is to press some buttons.

Boot into the calculator with battery+DEL and then:
1. Press any button besides ON - if the screen turns off, then the boot code is immediately throwing a link error
2. Press ON, then press any button besides ON - if the screen turns off, then the boot code is indeed waiting to receive an OS
3. If no amount of button mashing can get the screen to turn off, then you've got some serious problems (or you incorrectly entered battery+DEL)

I am having the same black screen problm with my ti-83+. i do not have a problem turning off my calculator. I tried steps 1 and 2. When I tried step 1 it did not turn off. When i tried step 2 the screen did turn off. Do you know how I can fix my calculator?

Hey guys, I just want to let you know my calc is OK.
After I tried all possible key combinations I just put the calc in the drawer and forgot about it.
Today I thought that I could try HW flashing of NAND (asking for a backup here) to see if that would help.
So I inserted fresh batteries, junk appeared on screen as before, "RAM cleared" message as before, but this time, after I pressed Clear button, it kept working!
My guess is that some friend in class did something that froze the calc while playing a game, and the batteries were low already, so it just couldn't reset completely or something, causing the junk on screen. Although I did try replacing batteries for the first time, looks like I really needed fresh ones, straight from the pack

Hey guys, I just want to let you know my calc is OK.
After I tried all possible key combinations I just put the calc in the drawer and forgot about it.
Today I thought that I could try HW flashing of NAND (asking for a backup here) to see if that would help.
So I inserted fresh batteries, junk appeared on screen as before, "RAM cleared" message as before, but this time, after I pressed Clear button, it kept working!
My guess is that some friend in class did something that froze the calc while playing a game, and the batteries were low already, so it just couldn't reset completely or something, causing the junk on screen. Although I did try replacing batteries for the first time, looks like I really needed fresh ones, straight from the pack

Good to hear that you don't need to buy a new one.

maby low baterries...
no just fun
 you turn it on and send a new os (ti connect is in sending os better then TiLP)