RN104 displays "NETGEAR Storage Welcome" every 1-2 seconds

It could be the power brick or a bad connection, but one suspect is the internal 3.3VSB (3.3V standby).  The 3.3VSB powers the power-on and Ethernet circuitry and is always on, even when the NAS is off, unless it's unplugged.  That can especially be the issue if the NAS is allowed to get very warm when "off", since the fans aren't running.  Check if the LAN LED is dim or blinking.  If it is, that probably confirms it.

A very short glitch on the input power might do it as well.  I believe the 1.4 will boot automatically if unplugged and plugged back in, and it may be starting to do that but not finishing.

I don't recall any history on a 104 having the 3.3VSB issue, but the 214 definitely does.  I have one I purchased for parts that has that issue and have read posts here about at least two others I suspect also had it.

Unfortunately, Netgear has never released schematics for ReadyNAS, so repair is pretty much out of the question.

At this point, it may not be causing you any issues, but if that is the 3.3VSB problem, you should prepare yourself for the day the NAS will fail to boot.