Stuck at switch: prompt

[swa64211]

Hey guys, I'm a beginner. While working on ESS 3300 switch, upon restart switch is stuck at switch prompt. There is no error message, just the following -

switch:
Initializing disk drivers...
SD Card is not present
Initializing file systems...
switch:

I tried to follow this procedure but it's not working.... it says boot command not recognized

Even basic commands like '?' ,'help' , 'dir' , 'boot' , etc are not being recognized

also if I press backspace the,"switch:" is also being erased

It'll really be very helpful for me if anyone can help..... thank you

[Deepak Kumar]

try with this command : 

boot emgy0:<image-name>.SPA.bin

 If you are still getting error msg. Can you past a screen shot. 

[swa64211]

Thank you, @Deepak Kumar for replying

When I executed that command, I'm getting an error-

"boot" command not recognized