problem automation process using telnet

i have a uclinux board which only support telnet. i can connect to board using below command:

[a,b] = system('d:\plink -telnet someIp)

after this command, board prompt me for username which isn't desirable. i have tried above command in two other formats. like:

[a,b] = system('d:\plink -telnet username@someIp)

and

[a,b] = system('d:\plink -telnet someIp -l username)

but it's no use and uclinux still ask for username. so i thought "maybe i can feed username into telnet session using m-file" as mentioned in this post.

https://www.mathworks.com/matlabcentral/answers/37025-matlab-to-telnet

but there is another problem. after telnet session got opend, i can't run any matlab script, it got blocked.