Help Galaxy s4 not even booting to recovery mode, sutck at S4 logo screen

[JMS23]

My unrooted phone gets stuck with the blue colour legend Recovery booting. I am unable to enter safe mode, any ideas? been surfing google for 6hrs with no proper answer. Thanks!

 

[afmracer6]

try entering recovery by holding three buttons the do a full reset wipe from recovery then restart

 

[JMS23]

try entering recovery by holding three buttons the do a full reset wipe from recovery then restart

which 3 buttons?
vol down goes to download mode, i am using MAC.
volume up as i said gets stuck with the blue font legend.