Send the following on WhatsApp
Continue to ChatDownload and Install HydrogenOS 3.0 on OnePlus 3/3T (Nougat based) https://www.stechguide.com/install-hydrogenos-3-0-on-oneplus-3-3t/
Download and Install HydrogenOS 3.0 on OnePlus 3/3T (Nougat based) https://www.stechguide.com/install-hydrogenos-3-0-on-oneplus-3-3t/