I'm trying to remember what I did when it was bad - and I think I just kept switching the ignition on and off to make it kick itself free - if your battery it 'fractionally past its best' then you'll be better off attaching jump leads from a car battery (with ign off) so you give it a very healthy voltage.
i had actually used a car battery to get it going albeit unsuccesful, but the squeel is coming from the lower end of the bike, not long had the new bearing but surely this wont stop it starting