not really a question as much as a comment that others may find useful...I tried 2 unsuccessful SP4 installations (after SP3Rollup1) and each time the install "ended prematurely"...then I remembered installing a SP way back and it recommended using an ELEVATED COMMAND PROMPT WITH VERBOSE LOGGING...which I did...and 3rd time was the charm!
msiexec.exe /p UAG-KB2861386-v4.0.4083.10000-ENU.msp /l*vx ExtraVerbose.log