Indeed, with the average mp3-file being 3 to 4 Mb there should go some 500 to 600 songs in 2 Gb.

Maybe there's other info stored on the player. Maybe your mp3-files are much bigger. Maybe it needs to be formatted. Maybe it isn't 2Gb at all. Maybe the file system is corrupted and you need to run a chkdsk.

If the device can function as a 'normal' USB-key, you can use Windows Explorer to have a look at the folders and files to see what's wrong.
If it's only accessible through Technica Application software, that might be more difficult. Read the user manual then.

Hope this helps.