ployer momo11 bird vol button won't work in u mode

[brown455]

I have tried to update firmware but the advice to hold down vol+ and press oower doesn't work. if I hold vol- and hold down the power then it shows a picture of the android on its back with ts stomach open and a yelow triangle. if i press the vol+ button then ut takes me to a black screen and a list of options such as formatting, reboot etc. It doesnt allow me to move through this menu at all and i can only press the power button that is (enter) and it reboots. Does anyne kniw what I'm doing wrong or if they have exoerience this issue.