The reason why oppo reno5 turns blue: OPPO phones start from ColorOS V3.2 version, if the power saving mode is enabled, the battery icon in the upper right corner will turn blue. It is recommended to activate the battery while charging in the future, so that the battery charging will have no memory. Charge from the AC socket, charge to 100% power off, and then charge until the green light turns on in shutdown mode. Boot into recover mode, select advancsd Advanced mode, and select wipe Battery to remove battery traces. Charge to 100% when you turn it on so your battery has no memory and it will charge much faster later
After the Power saving mode is enabled on the mobile phone, the color of the battery icon of the mobile phone is changed to blue, and the color is restored to the original color after the battery is turned off.