This is my path:
Jades-Nokia-N900-42-11:~# $PATH
-sh: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/bin/X11: not found

Following your instructions:
Jades-Nokia-N900-42-11:~# cd /usr/bin
Jades-Nokia-N900-42-11:/usr/bin# ./Jade_text
-sh: ./Jade_text: not found


The weird thing is I havent changed anything... it just stopped working straight after the firmware update.