I say, with Allah's guidance: Tayammum has two pillars: The first pillar: Two strikes: one strike for the face, and one strike for the hands up to the elbows: The order is not a condition but is recommended, like ablution; as narrated by Jabir , the Prophet  said: «Tayammum is two strikes: one for the face, and one for the arms up to the elbows», in Al-Mustadrak 1: 287, and authenticated, and Sunan Al-Daraqutni 1: 180, and Musannaf Ibn Abi Shaybah 1: 146. And from Al-Asla'  he said: «He showed me how the Messenger of Allah  taught him Tayammum: he struck the ground with his palms, then shook them, then wiped his face with them, then passed them over his beard, then returned them to the ground, then wiped the ground with them, then rubbed one with the other, then wiped his arms, both the outer and inner sides», in Sunan Al-Daraqutni 1: 179. The second pillar: Covering the face and hands with wiping according to the given fatwa: so that if a small part is left unwiped, it is not sufficient, just as if a hair or the edge of the nostril is left, and it requires removing the ring and bracelet, or moving it to ensure coverage. See: Sharh Al-Wiqayah p.106, and Al-Durr Al-Mukhtar 1: 158. And Allah knows best.