How is one washed if half of their body is as if burned by hot water due to prolonged lying on it and the length of their illness?

If a part of the deceased's body can be washed and rubbed with water without decomposing, then it must be washed accordingly. If rubbing causes harm, then only pouring water over it suffices. If pouring water over it is not possible, then the sound part of the body is washed, and the rest is subjected to tayammum (dry ablution). Thus, for someone who died from smallpox, burns, or drowning, if washing them is possible, they should be washed. If washing them risks dismemberment, then water should be poured over them. If pouring water over them risks dismemberment, then they should not be washed, but rather subjected to tayammum if possible. If washing the deceased is impossible due to lack of water, then tayammum should be performed. If washing a part of the body is impossible while another part is not, then whatever can be washed should be washed, and the rest subjected to tayammum.