you mentioned that you were getting error 16 after booting up. this is the error code you get when booting the original MS dash if some of the files are corrupted/missing.
First up, you're able to boot the Xenum OS screen so your chip install is fine.
From there, if this is a fresh install, you need to go 'launch menu' then 'add an item' then flash your original MS bios to the 'TSOP'
Once you've flashed your original bios to the TSOP, and providing your harddrive is locked, you'll be able to boot the original MS dashboard. If at this point you get 'error 16' you know your files for the original bios are messed up (corrupted or missing). In this case you'll need to get a new copy of them and ftp them back to your C: (if you get 'error 05' yourt harddrive is unlocked....use disk tools to lock it)
If the MS dash boots up fine, then congrats on a successful install and from there you need to flash another 'hacked' bios (like Xecuter II_5035) to your 'FLASH' bank on the modchip. After successfully flashing your bios to that bank, FTP the files for whatever dashboard you want to use into the C: (renaming the dashboards .xbe file to something your bios recognises) and you should be sweet.
All this is spelled out step by step in far greater clarity in 'The Iceguide'. Get a copy of this guide, figure out which steps you've already completed and follow along for the rest.