Can't boot Powerbook after zapping PRAM

["sipster" <spamROTZOOI@TROEP.calyx.euronet.nl>]

Hi,

I 've got a Powerbook 5300 cs just with OS8.5 on it.

After installing a pcmcia card the machine started to act weird so i zapped
the pram (which i understood is quite a normal thing to do when you wantto
bring the machine back in it's proper state)

Now i' m unable to start the machine in it's current configuration, i think
because the harddisk has been configured on another machine and then put
into my laptop. ( i send it off for a repair and reinstall, the machine was
not functioning when i got it first ) Now i'm left at a black screen after
startup after i resetted the pram following instructions.

I read some FAQ's & Manuals but i couldn't find any answer to my problem
yet.

I'm not able to start from a cdrom since this model does not have a cdrom
drive, i do have a comlete set of floppies with system 7.5.3 which i intend
to install now as a last option.. Since there is no important data on the
machine there's no problem with reinstalling the Operating System.

But i do get this message that there's already a system installed an the
setup is aborts after floppy 3 or 4 and i'm unable to proceed.

So now i have only three questions :

a) In which way will i be able to just start the installed system ? (i've
tried all keyboard 'CTRL' combinations at bootup).

b) How can i pass around the excisting installation and continue with the
installation from floppy.

c) How can i just wipe the whole enchelada and install my system 7.5.3 from
floppies without any problem (i have been looking for a boot manager,
unsuccesfully) and upgrade to a newer version afterwards via a network
connection or so.

 I will continue looking for info but some help is welcome here.

TIA!
Sipster