Flash will not work properly

Hi,
It may be the batteries, If using rechargeables one may be weak. try new batteries and check the battery contacts are all clean use a pencil eraser or a cotton bud (Qtip) moistened (not wet) with isopropyl alcohol (tape/stylus cleaning fluid)
If that dose'nt help Im sorry to say the flash is probably faulty as it would appear to be trying to charge but not reaching a full charge