the animation is short & without clear plot
tips - grenades usually need to have the pin removed to explode. Doing the motion of taking off the pin without actually showing the pin being removed and tossed isn't sufficient. Your explosion did indeed suck, and the only thing I can offer for advice towards improving is you should remember explosions tend to cause a quick burst of light (quickly fade to white screen and back is an option) then followed by the already going flames and smoke. Drawing squiggly red and yellow lines is also insufficient. Good luck with further animations. Compared to other "noob"s, you actually have potential.