I dont remember 5 blinks but most Sony shut down problems
are cold joints at the vertical out IC & at the horz drive transformer.
Other reasons I remember are: no vert, too much HV, Horz over current,
failure to achieve acceptable grey scale & a few more.
As far as the default problem goes you probably wont find it. Something
like that will send a tech running for the door. For a few years you could
get whole boards for something like that but they are soon gone or
sold off as scrap.
Oh has anyone been in the service menus ????
73 Zeno
LFOD !