DSO- 1200 not powering on

sushilx

Dear  All

Mu DSO 1200  (version 1.05) was not used for long time.

now the device is not powering on, it gives  beep sound when i press the on button.
no  display.

any one can share scematics or troubleshooting  idea is very help full.

The battery is full charged, i confirmed.

thanks in advance