Dear Sir,
Regards to your PDF - The problem with keyboard language. There are 2 solutions you may try:
1. You may un-install the Thai keypad software first then re-install your Thai keypad software. Then try again.
2. Try to do a manual reset on your MC-5380, then you re-install your Thai keypad software. Then try again.
Please let me know the results.
Your reply is highly appreciate.