96 hitachi 200lc3 excavator hydraulic issue

I got a hitachi 200lc3 when u go to move the bucket or anythink to do with hydraulics the motor stalls.., it's acting like it's under load smoking black no power someone told me it's the high pressure selenoid .., could that b my problem and if so how do I check them ? And also I was told I could eliminate the computer is this true ? Need help thanks