Hi, firstly if this is in the wrong place i apologise, and i have also looked for 3 days for an answer to my question but without any luck. If i have missed it - many apologies.
Ok here goes: -

I have a modded xbox which has been working fine for the last 6 months, however it will now not boot a couple of my backups (just hangs at startup - black screen or hangs at Big green x at start). I can accept that but it wont play the originals of my backups either??? (Namely 2 titles in question). What i cant understand is - it will still boot other backups and originals just not these two?
I am a slight noob but i am technically minded . I am prepared to flash the bios (recommendation of a friend as he said update it), but when i use bios-checker (to know where i am starting)it says "Unknown Bios"
The chip i did find out is a sst49FL020 (not a), but i have no idea what chip is inside as i dont really want to open it! I cant take it back to place that modded it as i live miles away now - so question is a)I have slayers 2.6 - can i flash my bios with this and how risky is it??
b)Does anyone recommend or know what bios to use? (Person that modded it said it had to be 256k and maybe m8 if that helps?)
Sorry if this is painfully easy to someone but i am well stuckand i have tried looking everywhere!
I have posted all relevent info i can below:

Running evoX dash
Kernal 1.00.5101.01
Version: Unsure as link on Xbox-scene is dead (serial ends in 05 = China)
Does NOT have xecuter 2 at startup screen
Does have abilty to disable mod on pressing of eject/holding power button (does that help?)

I reapply appreciate anybody even taking the time to read this!.. Thanks

Before you flash the bios. disable the chip when you boot so it boots the original M$ bios? If so do the originals play ok using the normal M$ bios?
If they do then maybe flashing the bios on the chip will help. You need to find out the version before you flash which may entail opening the box and having a look to see what video encoder you have in the machine (Chip will have on it Connexant, Focus or xcalibur)
If the originals still don't play on the ordinary bios then I don't think it has anything to do with the bios on the chip but is more likely a problem with your Xbox. Updating to the latest M$ dash may help.

It works with other originals, just not these particular titles (EA is a clue) In all respects the mod works fine, just not on these. If it is better to just leave it alone and suffer without these i dont mind - just thought i would ask advice of people that know way more than me!. I will open box tomorro after work and see.
Thanks for reply though - will get back to u tomorro on version.

But do these EA originals work with the chip in the off mode? You can mention the game titles of originals on here by the way.

Not for the titles of tiger woods 2004 AND 2005 no it doesnt. Either with mod chip on or "off". This is what i find really weird as all my other originals and backups work ok... its just twoods?.. I tried all the combinations i could of chip on with disc/on then put in disc etc.. none work. I even tried putting in original that did work first then tiger woods.. but that still didnt work! I just think my xbox doesnt want me to play this particular game

It must be something other than the modchip bios then. tiger woods 2005 works on my version 1 and both 1.6 versions

ok, here is some more info:

Kernal 5101
(From evox.ini) - Current = 0x71298c758387c2acba525a2f7406e2be (does not match with ANY bios on the list on xbox-scene? - So how the hell do i know what bios i have??
Version of xbox is either 1.2 or 1.3 from tuts (dead link for linux page still!)
So my question still stands - What 256k bios can i safefully flash with??... Can i use the 256k ones that come with slayers 2.6?.. sorry for being a pain, but i just have come to a dead halt

a 5101 is like a 1.4 or 1.5 box, so you should be able to flash any of the new bios out. Dont flash with M8_16 because as far as I know it wont work too well, if at all on a non 1.6 machine. Stick with a M8, or get the Xecuter bios. I dont think the evox bio information means much at all... So ignore that.

ok, that sounds like good advice... the manufacture date is 2003-05-09, dunno if that helps with what version i have. Gonna flash with the Evox-m8 flash option 5b2 on slayers (Have retail hard drive so no need for the 137gb bit)... wont do it till tomorro night so if anyone sees fit why i shouldnt do it.. please let me know.. thanks to all those who posted a reply - appreciate the guidance!

Sounds like a 1.4 so you could use X2 4981 or whatever really. The slayers one will be fine.
It won't cure the problems of playing the originals through the M$ bios though as obviously that would not be changed.
You could try them with the chip on though