DFPLAYER problem

HI guys,
My name is DAVID from HK, nice to meet you guys here, i am first time post topic here, if i am post wrong place, please move it, thank you.

i am now making a project using arduino micro pro with DFplayer. it will play five tracks.
(please see the attachment)

but i got a problem, the first track only will play after using arduino IDE upload the code to the board…if i using battery as power source. or using power blank it will not play the first tracks…but the funny thing is that after the fifth track played, at the next loop the first will play.

but it will play as normal if i using arduino UNO…

i have already checked the file is ok, the connection is ok, the battery is ok.
because it was not “it will never play the first track”, it is “will not play the first track when every time the device is turn on…but it will play at the next loop”

Thank you for the help.

micropro.ino (1.24 KB)