ALL THE LCD SCREENS ARE BLANK I PUT NEW BATTERIE AND STILL THE SAME

LCD fitting instruction videos for most phones can be found on youtube.

take the batterie out and put it back on

possible that the flex holding the lcd is broken.

unscrew it and change the flex to enable it view programms

please see for the technician the problems is in the LCD of the phone you might have to replace it.

It is just an issue with the lcd. they run about 45 dollars on ebay and are fairly easy to replace.

If you are strapped for cash, try this fix first Fix Sidekick White LCD Screen

If that doesn't help then here is the procedure to replace the lcd.
replacement of the Sidekick 3 LCD flip screen.

And here is a link to the screens on ebay. Buy one with the whole flip assy. It is much easier to replace than the lcd screen itself.
http://www.repairmysidekick.org/SideKick-Repair-Parts/Sidekick-LCD-Screens

Is it white or just black?

If it it is white then this procedure should fix it, Fix Sidekick White LCD Screen

if it is black then a new lcd is in order. They run about 45 dollars and fairly simple to install.
http://www.repairmysidekick.org/SideKick-Repair-Parts/Sidekick-LCD-Screens

If it powers on and your screen is blank then you need a new lcd screen. They run about 45 dollars and are super easy to replace.

Sidekick LCD screens

Sidekick 3 LCD flip screen replacement guide

Check out the following link. Most of the Screens come with instructions and the screwdriver you will need. You can probably search on ebay for your other phone as well

Sidekick LCD screens

try reflash the phone or replacing the lcd