OS X 10.2.8 upgrade: my YDL 3 can't boot

[massimo]

Hello,
i know, it is an old problem and I tried everithing possible, but i 
can't overcome it.
In a firts time (one week ago), I updated osx on the powerbook G4 867 
12"  from the 10.2.6 to 10.2.8 version, supposing was the fixed 
upgrade, but my YDL 3.0 that before worked very well, was not able to 
boot.
Yesterday,
	I partitioned and formatted the disk,
	I installed OS X 10.2.2,
	I installed YDL 3,
		but it did not boot,
then,
	I upgraded OSX 10.2.2 to 10.2.6 (combo upgrade),
		still YDL did't boot
finally,
	I upgraded OSX 10.2.6 to 10.2.8,
		but, still YDL did not boot

Now, I don't know what else can I do.
I'd like avoid to upgrade the linux kernel as suggested by sameone, 
because the complexity of the task, but if it is inevitable ....
Probably, the problem is about an update of the firmeware (performed by 
10.2.8 upgrade in order to manage better the Nvidia geoforce 4). If is 
there something I can do, like downgrade or reset of the Open Firmware.

Please help me, any suggest is greatly wellcome

thank you,

Massimo