Hi!

Error 16 means the console can't load its dashboard.

The HDD is locked with an EEPROM code, for the original Xbox. You can't just swap it. The code on the motherboard must match with the HDD it's code.

If your original HDD is broken, it could display the same 16 error.

There is a way to get the code from the motherboard, but you do need the proper tools to get the code > Guide: https://www.youtube.com/watch?v=uzrljlHD...

Also, you need to get Xbox it's software installed on the new HDD before you can put it in again.

When it's modded with a modchip, you can put in any drive you like. *software does still need to be installed* (make sure the new HDD is unlocked), afterwards you can lock the new hard drive with the motherboard it's EEPROM code. Some unofficial applications can retrieve the code from the motherboard and lock the new HDD.

Here you can find the application to restore the Xbox software on the HDD: https://fatxplorer.eaton-works.com/ (it only works when the hard disk is unlocked).

I can't help you with the modding part unfortunately... But those are the only ways to get your Xbox ready with a new HDD.

If you have any questions, please let us know!