Casio TK2200. no response from any of the key. It is switched on

Adjusting Display Brightness You can use the following procedures to adjust display brightness to make it easier to
read under different lighting conditions.
Press the "Fn" key and then press the "5" key or "6" key after con? rming that "F"
is displayed in the lower right corner of the screen. Pressing the "5" key adjusts
brightness for a darker display, while pressing the "6" key adjusts brightness for a
lighter display.
In order to continue to make adjustments, press the "5" key or "6" key again after
? rst pressing the "Fn" key.
Brightness settings can also be made by navigating to the menus and tab in order of
Start ? Settings ? System ? Backlight.
The manual is here:
Casio IT 800 Series User Manual

I would suggest a factory data reset. Backup your files you want to keep first!


1. When the phone is switched off, press
and hold the Volume down key +
Power key with your left hand.

2. When the LED on the bottom of the phone
lights up, touch and hold the Menu key
with your right hand. You need to do this
immediately, before the screen displays the
LG logo. Make sure your left hand is still
holding the Volume down and Power keys.
Then release the power key at vibration time.

3. When the LG logo is displayed on the
screen, continue to hold the keys for
around 2 seconds, and then release all
them at the same time, before the LG
logo disappears.
Leave your phone for at least a minute while
the hard reset is carried out. You will then be
able to switch your phone back on.

Brand and model?

No, they're not related.

To switch the radix mark, turn the calculator off, press and hold the decimal point key, press the ON key, then release both keys.

No, they're not related.

To switch the radix mark, turn the calculator off, press and hold the decimal point key, press the ON key, then release both keys.

Press the"SHIFT" button in the top left corner, then the "MODE" button on the top right.
Select 2: Line10

This will always give you a decimal answer. When you want to switch back to fraction, just select number 1:Mth10

To switch the radix mark between the US and European modes, press the yellow shift key then the ./, key on the bottom row of the keyboard between the 0 and = keys.

To switch the radix point between the US and European modes, press and hold the decimal point key, press and release the ON key, then release the decimal point key.

HI..if this is a printing calculator and the print mode is turned...if there is a problem with the printer and E for Error will appear. The ribbon or some paper could be jammed in the printer..a key could be stuck down..check your entire keyboard key for sticking.
The calculator wont hurt itself and that is why the E is on. Examine it very carefully and look for something caught in it.
If none of the above you might have to get a pro to look at it.
Hope this helps you out....
Squipps

To remove the comma, turn off the calculator. With it turned off, push and hold down the [ON] key. While still depressing the [ON] key, push and hold down the decimal or [.] key. Now you should have them both held down. Now, release ONLY the [ON] key.

To remove the "c", push then release the [STO] key. Then push and release the [EEX] key.