Give it a charge.
Most lipo batteries should be safe to go down to 2.8v per cell (5.6v)
Due to current drain and use its suggested to us 3v per cell (6v) as a minimum.
If you have a esc with a adjustable cuttoff its wise to keep it a bit higher at 3.2v per cell (6.4v)
casterracing EX-1 Pro, SP Silver Arrow
TOP Racing Scythe, SP 17.5, SP GT Pro 2.0
TOP Racing Scythe, SP 4.5 V2, Hobbywing Xerun 120SD 2.0
TOP Racing Scythe, SP 13.5, Hobbywing Xerun 120SD 2.0